# Scheduler Zero

> The cold email outreach platform built for deliverability. Warm up domains, schedule sequences, and manage every reply from one inbox.

Scheduler Zero helps cold-email senders land in the primary inbox. The pages below are practical, vendor-neutral references on email deliverability, authentication, and sending hygiene, plus free in-browser tools. Every page is real data, not boilerplate.

Append `.md` to any page URL on this site for a clean Markdown version. The full text of every reference page is also at /llms-full.txt.

## Free tools

- [MX Record Lookup](https://www.schedulerzero.com/tools/mx-lookup.md): Look up a domain's MX records (the mail servers that receive its email), in priority order.
- [DNS Lookup](https://www.schedulerzero.com/tools/dns-lookup.md): Look up any DNS record (A, AAAA, MX, TXT, CNAME, NS) for a domain, live.
- [SPF Record Checker](https://www.schedulerzero.com/tools/spf-checker.md): Find and validate a domain's SPF record: syntax, the 10-lookup limit, and the all qualifier.
- [DKIM Record Checker](https://www.schedulerzero.com/tools/dkim-checker.md): Look up a domain's DKIM public key at a given selector and confirm it is published.
- [DMARC Record Checker](https://www.schedulerzero.com/tools/dmarc-checker.md): Find and parse a domain's DMARC record: policy, reporting address, and alignment.
- [Email Signature Generator](https://www.schedulerzero.com/tools/email-signature-generator.md): Build a clean, lightweight HTML email signature and copy it in one click.

## Calculators

- [Email Deliverability Rate Calculator](https://www.schedulerzero.com/calculators/deliverability-rate.md): Work out your delivery and inbox-placement rates from sends, bounces, and spam placements.
- [Domain Warmup Calculator](https://www.schedulerzero.com/calculators/domain-warmup.md): Estimate how many days it takes to warm a new domain up to your target daily volume.
- [Safe Sending Volume Calculator](https://www.schedulerzero.com/calculators/safe-sending-volume.md): Find a safe daily cold-email volume across your sending inboxes without torching reputation.
- [Cold Email ROI Calculator](https://www.schedulerzero.com/calculators/cold-email-roi.md): Project meetings, deals, revenue, and ROI from your cold email volume and funnel rates.

## Deliverability glossary

- [Sender Policy Framework (SPF)](https://www.schedulerzero.com/glossary/spf.md): An email authentication standard that lets a domain publish which mail servers are authorized to send on its behalf.
- [DomainKeys Identified Mail (DKIM)](https://www.schedulerzero.com/glossary/dkim.md): An authentication method that cryptographically signs outgoing email so recipients can verify it was not altered and came from the claimed domain.
- [Domain-based Message Authentication, Reporting and Conformance (DMARC)](https://www.schedulerzero.com/glossary/dmarc.md): A policy layer built on SPF and DKIM that tells receivers how to handle mail that fails authentication and where to send reports.
- [Domain Name System (DNS)](https://www.schedulerzero.com/glossary/dns.md): The global directory that maps domain names to IP addresses and stores the records that govern email routing and authentication.
- [TXT Record](https://www.schedulerzero.com/glossary/txt-record.md): A DNS record type that holds arbitrary text, used to publish SPF, DKIM, and DMARC authentication policies.
- [MX Record (Mail Exchange Record)](https://www.schedulerzero.com/glossary/mx-record.md): A DNS record that specifies which mail servers receive email for a domain, in priority order.
- [CNAME Record (Canonical Name Record)](https://www.schedulerzero.com/glossary/cname-record.md): A DNS record that aliases one hostname to another, commonly used for custom tracking domains and delegated DKIM.
- [Return-Path](https://www.schedulerzero.com/glossary/return-path.md): The address where bounces and delivery failures are sent, and the domain SPF authenticates against.
- [Envelope Sender (MAIL FROM)](https://www.schedulerzero.com/glossary/envelope-sender.md): The address given in the SMTP MAIL FROM command that identifies the true sender for routing and bounces.
- [Header From (From: Header)](https://www.schedulerzero.com/glossary/header-from.md): The visible From address recipients see, and the identity DMARC alignment is measured against.
- [DMARC Alignment](https://www.schedulerzero.com/glossary/dmarc-alignment.md): The requirement that an authenticated SPF or DKIM domain match the visible From domain for DMARC to pass.
- [DMARC Policy](https://www.schedulerzero.com/glossary/dmarc-policy.md): The instruction in a DMARC record (none, quarantine, or reject) telling receivers how to handle mail that fails authentication.
- [Brand Indicators for Message Identification (BIMI)](https://www.schedulerzero.com/glossary/bimi.md): A standard that displays your verified brand logo next to authenticated messages in supporting inboxes.
- [Authenticated Received Chain (ARC)](https://www.schedulerzero.com/glossary/arc.md): A protocol that preserves email authentication results across forwarding and intermediaries.
- [Mail Transfer Agent (MTA)](https://www.schedulerzero.com/glossary/mta.md): The server software that routes and delivers email between domains using SMTP.
- [Mail Transfer Agent Strict Transport Security (MTA-STS)](https://www.schedulerzero.com/glossary/mta-sts.md): A policy that forces inbound mail to your domain to be delivered over validated, encrypted TLS.
- [Spam Trap (Honeypot)](https://www.schedulerzero.com/glossary/spam-trap.md): An email address used solely to catch senders with poor list hygiene or no permission.
- [Catch-All (Accept-All) Domain](https://www.schedulerzero.com/glossary/catch-all.md): A domain that accepts mail for any address, real or not, making verification uncertain.
- [Hard Bounce](https://www.schedulerzero.com/glossary/hard-bounce.md): A permanent delivery failure, usually because the recipient address does not exist.
- [Soft Bounce](https://www.schedulerzero.com/glossary/soft-bounce.md): A temporary delivery failure that may succeed on a later retry.
- [Bounce Rate](https://www.schedulerzero.com/glossary/bounce-rate.md): The percentage of sent messages that fail to deliver and bounce back.
- [IP Warming](https://www.schedulerzero.com/glossary/ip-warming.md): Gradually increasing send volume on a new IP to build a positive sending history.
- [Domain Warming](https://www.schedulerzero.com/glossary/domain-warming.md): Gradually ramping volume and engagement on a new sending domain to establish reputation.
- [Sender Reputation](https://www.schedulerzero.com/glossary/sender-reputation.md): A mailbox provider's trust score for a sending IP and domain that drives inbox placement.
- [Sender Score](https://www.schedulerzero.com/glossary/sender-score.md): A 0 to 100 reputation rating that estimates how trustworthy a sending IP address looks to mailbox providers.
- [Blacklist (DNSBL / Blocklist)](https://www.schedulerzero.com/glossary/blacklist.md): A published list of IP addresses or domains known for spam that mail servers consult to block or filter incoming messages.
- [Realtime Blackhole List (RBL)](https://www.schedulerzero.com/glossary/rbl.md): A DNS-queryable blacklist that lets receiving servers check a sender's IP reputation in real time during the SMTP handshake.
- [Greylisting](https://www.schedulerzero.com/glossary/greylisting.md): An anti-spam tactic where a server temporarily rejects mail from unknown senders and accepts it only on a retry.
- [Spam Complaint](https://www.schedulerzero.com/glossary/spam-complaint.md): The event of a recipient marking a message as spam or junk, signaling the mailbox provider that the mail was unwanted.
- [Complaint Rate](https://www.schedulerzero.com/glossary/complaint-rate.md): The percentage of delivered emails that recipients mark as spam over a given period.
- [Feedback Loop (FBL)](https://www.schedulerzero.com/glossary/feedback-loop.md): A program by which a mailbox provider forwards spam complaints back to the sender so they can suppress those recipients.
- [List Hygiene](https://www.schedulerzero.com/glossary/list-hygiene.md): The ongoing practice of cleaning a contact list to remove invalid, risky, or unengaged addresses before sending.
- [Double Opt-In](https://www.schedulerzero.com/glossary/double-opt-in.md): A subscription method requiring the recipient to confirm via a follow-up email before being added to a list.
- [Single Opt-In](https://www.schedulerzero.com/glossary/single-opt-in.md): A subscription method that adds a recipient to a list immediately after signup with no email confirmation step.
- [Open Rate](https://www.schedulerzero.com/glossary/open-rate.md): The percentage of delivered emails that recipients opened, usually measured via a tracking pixel.
- [Reply Rate](https://www.schedulerzero.com/glossary/reply-rate.md): The percentage of delivered cold emails that generate a reply from the recipient.
- [Deliverability](https://www.schedulerzero.com/glossary/deliverability.md): The ability of your emails to reach recipients' inboxes rather than being blocked or filtered to spam.
- [Inbox Placement](https://www.schedulerzero.com/glossary/inbox-placement.md): The share of delivered emails that land in the primary inbox rather than spam or a secondary tab.
- [Spam Folder](https://www.schedulerzero.com/glossary/spam-folder.md): The junk folder where mailbox providers quarantine messages judged to be unwanted or risky.
- [Dedicated IP Address](https://www.schedulerzero.com/glossary/dedicated-ip.md): A sending IP address used by only one sender, giving you sole ownership of its reputation.
- [Shared IP Address](https://www.schedulerzero.com/glossary/shared-ip.md): A sending IP used by multiple senders who collectively shape its reputation.
- [Email Authentication (SPF, DKIM, DMARC)](https://www.schedulerzero.com/glossary/email-authentication.md): The DNS-based protocols that prove an email genuinely came from your domain.
- [Google Postmaster Tools (GPT)](https://www.schedulerzero.com/glossary/google-postmaster-tools.md): Google's free dashboard reporting how Gmail rates your domain's sending reputation and spam rate.
- [Spam Rate (Complaint Rate)](https://www.schedulerzero.com/glossary/spam-rate.md): The percentage of delivered emails that recipients mark as spam.
- [Subdomain](https://www.schedulerzero.com/glossary/subdomain.md): A prefixed segment of your root domain (e.g. mail.example.com) used to isolate sending reputation.
- [Simple Mail Transfer Protocol (SMTP)](https://www.schedulerzero.com/glossary/smtp.md): The internet standard protocol for sending and relaying email between servers.
- [IMAP (Internet Message Access Protocol)](https://www.schedulerzero.com/glossary/imap.md): A protocol for reading and managing email on a remote mail server while messages stay stored server-side.
- [POP3 (Post Office Protocol version 3)](https://www.schedulerzero.com/glossary/pop3.md): An older protocol that downloads email to a single client and usually removes it from the server.
- [SMTP Relay](https://www.schedulerzero.com/glossary/smtp-relay.md): A mail server or service that accepts outbound email and forwards it on toward the recipient's mail server.
- [ESP (Email Service Provider)](https://www.schedulerzero.com/glossary/esp.md): A platform that hosts mailboxes or sends email on your behalf, managing delivery infrastructure and authentication.
- [TLS (Transport Layer Security)](https://www.schedulerzero.com/glossary/tls.md): The encryption protocol that secures email in transit between mail clients and servers.
- [STARTTLS](https://www.schedulerzero.com/glossary/starttls.md): A command that upgrades a plaintext email connection to encrypted TLS on the same port.
- [PTR Record (Pointer Record)](https://www.schedulerzero.com/glossary/ptr-record.md): A reverse-DNS record that maps a sending IP address back to a hostname.
- [Reverse DNS (rDNS)](https://www.schedulerzero.com/glossary/reverse-dns.md): The lookup that resolves an IP address back to a hostname, the opposite of normal DNS resolution.
- [A Record (Address Record)](https://www.schedulerzero.com/glossary/a-record.md): A DNS record that maps a hostname to an IPv4 address.
- [NS Record (Name Server Record)](https://www.schedulerzero.com/glossary/ns-record.md): A DNS record that delegates a domain to the authoritative name servers responsible for its zone.
- [TTL (Time To Live)](https://www.schedulerzero.com/glossary/ttl.md): The number of seconds DNS resolvers are allowed to cache a record before re-querying it.
- [DNS Propagation](https://www.schedulerzero.com/glossary/dns-propagation.md): The delay before a DNS change is visible everywhere as cached copies of the old record expire.
- [SPF Flattening](https://www.schedulerzero.com/glossary/spf-flattening.md): Replacing the include mechanisms in an SPF record with resolved IP addresses to stay under the DNS lookup limit.
- [SPF PermError (Permanent Error)](https://www.schedulerzero.com/glossary/spf-permerror.md): A permanent SPF evaluation failure caused by an invalid or unprocessable SPF record, most often from exceeding the 10 DNS-lookup limit.
- [DKIM Selector](https://www.schedulerzero.com/glossary/dkim-selector.md): The label in a DKIM signature that tells receivers which public key to fetch from DNS to verify the message.
- [List-Unsubscribe Header](https://www.schedulerzero.com/glossary/list-unsubscribe.md): An email header (RFC 2369) that gives mailbox providers a machine-readable way to let recipients unsubscribe directly from the inbox.
- [One-Click Unsubscribe (RFC 8058)](https://www.schedulerzero.com/glossary/one-click-unsubscribe.md): A standard that lets a recipient unsubscribe with a single click, with no confirmation page or login, via an automated POST request.
- [CAN-SPAM Act](https://www.schedulerzero.com/glossary/can-spam.md): The US federal law setting rules for commercial email, including honest headers, a valid physical address, and a working opt-out.
- [GDPR (General Data Protection Regulation)](https://www.schedulerzero.com/glossary/gdpr.md): The EU data-protection law governing how personal data, including business email addresses, is collected and used for outreach.
- [CASL (Canada's Anti-Spam Legislation)](https://www.schedulerzero.com/glossary/casl.md): Canada's strict consent-based email law requiring permission before sending commercial messages to Canadian recipients.
- [Bulk Sender Requirements (Gmail and Yahoo 2024)](https://www.schedulerzero.com/glossary/bulk-sender-requirements.md): The 2024 Gmail and Yahoo rules high-volume senders must meet to keep reaching the inbox: authentication, easy unsubscribe, and a low spam rate.
- [Domain Reputation](https://www.schedulerzero.com/glossary/domain-reputation.md): A mailbox provider's trust score for your sending domain, built from authentication, engagement, complaints, and spam-trap hits.
- [IP Reputation](https://www.schedulerzero.com/glossary/ip-reputation.md): A mailbox provider's trust score for the specific IP address that delivers your mail.
- [Seed List](https://www.schedulerzero.com/glossary/seed-list.md): A set of monitored test inboxes across major providers used to measure where your email actually lands.
- [Spam Score](https://www.schedulerzero.com/glossary/spam-score.md): A numeric rating of how spammy a message looks, summed from rule hits by a content filter such as SpamAssassin.
- [Apache SpamAssassin](https://www.schedulerzero.com/glossary/spamassassin.md): A widely used open-source spam filter that scores email against hundreds of rules to decide whether it is spam.
- [Delivery Rate](https://www.schedulerzero.com/glossary/delivery-rate.md): The percentage of sent emails accepted by recipient mail servers rather than bounced.
- [Transactional Email](https://www.schedulerzero.com/glossary/transactional-email.md): A one-to-one email triggered by a specific user action or account relationship, such as a password reset or receipt.
- [Marketing Email](https://www.schedulerzero.com/glossary/marketing-email.md): A bulk commercial message promoting products, offers, or content sent to a list of opted-in recipients.
- [Cold Email](https://www.schedulerzero.com/glossary/cold-email.md): Unsolicited outreach sent to a recipient who has no prior relationship with the sender, typically for B2B sales prospecting.
- [Drip Campaign](https://www.schedulerzero.com/glossary/drip-campaign.md): An automated series of emails delivered on a fixed schedule or in response to recipient behavior.
- [Email Sequence](https://www.schedulerzero.com/glossary/email-sequence.md): An ordered set of automated emails, most often an initial message plus timed follow-ups, sent until a recipient responds or the sequence completes.
- [Personalization](https://www.schedulerzero.com/glossary/personalization.md): Tailoring an email's content to the individual recipient using their attributes or context rather than sending an identical message to everyone.
- [Spintax (Spinning Syntax)](https://www.schedulerzero.com/glossary/spintax.md): A syntax using brace-delimited alternatives like {hi|hello|hey} to generate many slightly different versions of the same message.
- [Merge Tag](https://www.schedulerzero.com/glossary/merge-tag.md): A placeholder token in an email template that is replaced with recipient-specific data from a list or CRM at send time.
- [Custom Tracking Domain](https://www.schedulerzero.com/glossary/custom-tracking-domain.md): A branded domain or subdomain you own, pointed at your ESP's tracking host, used to serve open pixels and click-redirect links under your own name.
- [Open Tracking](https://www.schedulerzero.com/glossary/open-tracking.md): A technique that detects when a recipient opens an email, usually by embedding a tracking pixel that loads from a server.
- [Click Tracking](https://www.schedulerzero.com/glossary/click-tracking.md): Measuring link clicks by rewriting URLs to route through a redirect server that logs the click before forwarding the recipient.
- [Tracking Pixel](https://www.schedulerzero.com/glossary/tracking-pixel.md): A tiny transparent image embedded in an HTML email whose load from the server signals that the message was opened.
- [Unsubscribe Rate](https://www.schedulerzero.com/glossary/unsubscribe-rate.md): The percentage of delivered recipients who opt out of future messages via an unsubscribe link or header.
- [Engagement Rate](https://www.schedulerzero.com/glossary/engagement-rate.md): A composite measure of how recipients interact with your emails, combining opens, clicks, and replies relative to messages delivered.
- [Promotions Tab](https://www.schedulerzero.com/glossary/promotions-tab.md): Gmail's tabbed-inbox category where bulk, promotional, and marketing-style mail is automatically sorted, separate from the Primary tab.
- [SMTP (Simple Mail Transfer Protocol) Error Code](https://www.schedulerzero.com/glossary/smtp-error-code.md): The numeric reply code an SMTP server returns to indicate whether a message was accepted, temporarily deferred, or permanently rejected.
- [Role Account (Role-Based Address)](https://www.schedulerzero.com/glossary/role-account.md): A shared, function-based mailbox such as info@, sales@, or support@ that is tied to a role rather than a specific person.
- [Disposable Email (Disposable Email Address)](https://www.schedulerzero.com/glossary/disposable-email.md): A temporary, throwaway email address from a short-lived service that is designed to expire or be abandoned quickly.
- [Honeypot](https://www.schedulerzero.com/glossary/honeypot.md): An email address or web form field deliberately planted to catch spammers and scrapers, with no legitimate reason to ever receive mail.
- [Snowshoe Spam](https://www.schedulerzero.com/glossary/snowshoe-spam.md): A spam technique that spreads sending across many IP addresses and domains to keep any single one below reputation-based detection thresholds.
- [Backscatter (Collateral Spam)](https://www.schedulerzero.com/glossary/backscatter.md): Misdirected bounce messages or auto-replies sent to an innocent address that was forged as the sender of spam.
- [URIBL (Uniform Resource Identifier Block List)](https://www.schedulerzero.com/glossary/uribl.md): A DNS-based blocklist of domains and URLs found inside message bodies, used to filter mail that links to known-bad sites.
- [Mailbox Provider (MBP)](https://www.schedulerzero.com/glossary/mailbox-provider.md): The company that operates the receiving email infrastructure and inboxes for recipients, such as Google, Microsoft, or Yahoo.
- [Microsoft SNDS (Smart Network Data Services)](https://www.schedulerzero.com/glossary/microsoft-snds.md): Microsoft's free portal that reports IP reputation, traffic, and spam data for senders mailing into Outlook, Hotmail, and Live.

## Spam trigger words

- [Spam trigger words to avoid in cold email](https://www.schedulerzero.com/spam-trigger-words.md): 78 words and phrases that raise spam risk, grouped by why they hurt.

## Sending limits

- [Gmail sending limits](https://www.schedulerzero.com/sending-limits/gmail.md): Gmail sending limits and inbox-safe cold-email volume.
- [Google Workspace sending limits](https://www.schedulerzero.com/sending-limits/google-workspace.md): Google Workspace sending limits and inbox-safe cold-email volume.
- [Outlook.com sending limits](https://www.schedulerzero.com/sending-limits/outlook-com.md): Outlook.com sending limits and inbox-safe cold-email volume.
- [Microsoft 365 sending limits](https://www.schedulerzero.com/sending-limits/microsoft-365.md): Microsoft 365 sending limits and inbox-safe cold-email volume.
- [Yahoo Mail sending limits](https://www.schedulerzero.com/sending-limits/yahoo.md): Yahoo Mail sending limits and inbox-safe cold-email volume.
- [Zoho Mail sending limits](https://www.schedulerzero.com/sending-limits/zoho-mail.md): Zoho Mail sending limits and inbox-safe cold-email volume.
- [Amazon SES sending limits](https://www.schedulerzero.com/sending-limits/amazon-ses.md): Amazon SES sending limits and inbox-safe cold-email volume.
- [SendGrid sending limits](https://www.schedulerzero.com/sending-limits/sendgrid.md): SendGrid sending limits and inbox-safe cold-email volume.

## SPF/DKIM/DMARC setup

- [Set up SPF, DKIM, and DMARC on GoDaddy](https://www.schedulerzero.com/setup/email-authentication/godaddy.md): Add SPF, DKIM, and DMARC as TXT records in GoDaddy's DNS records editor (Domain Portfolio → your domain → DNS → Add New Record), using @ for the root and...
- [Set up SPF, DKIM, and DMARC on Cloudflare](https://www.schedulerzero.com/setup/email-authentication/cloudflare.md): Add SPF, DKIM, and DMARC as TXT records under DNS > Records in the Cloudflare dashboard, using @ for the root and _dmarc for DMARC, with no surrounding...
- [Set up SPF, DKIM, and DMARC on Namecheap](https://www.schedulerzero.com/setup/email-authentication/namecheap.md): How to add SPF, DKIM, and DMARC TXT records in Namecheap's Advanced DNS - the exact menu path, host-field conventions (@, _dmarc, selector._domainkey),...
- [Set up SPF, DKIM, and DMARC on Squarespace Domains (formerly Google Domains)](https://www.schedulerzero.com/setup/email-authentication/squarespace-domains.md): Add SPF, DKIM, and DMARC as TXT records under Custom Records in your Squarespace domain's DNS Settings, using "@" for the root and "_dmarc" (no domain...
- [Set up SPF, DKIM, and DMARC on AWS Route 53](https://www.schedulerzero.com/setup/email-authentication/aws-route-53.md): Add SPF, DKIM, and DMARC as TXT records in your domain's Route 53 hosted zone using Create record — every value must be wrapped in double quotes, and DKIM...
- [Set up SPF, DKIM, and DMARC on Bluehost](https://www.schedulerzero.com/setup/email-authentication/bluehost.md): Add SPF, DKIM, and DMARC as TXT records in Bluehost's "Manage Advanced DNS Records" area under Domains → DNS (or the cPanel Zone Editor on legacy/cPanel...
- [Set up SPF, DKIM, and DMARC on Hostinger](https://www.schedulerzero.com/setup/email-authentication/hostinger.md): Add SPF, DKIM, and DMARC as TXT records in Hostinger's hPanel DNS Zone Editor, using @ for the root domain and _dmarc for DMARC — only works when the...
- [Set up SPF, DKIM, and DMARC on IONOS](https://www.schedulerzero.com/setup/email-authentication/ionos.md): Add SPF, DKIM, and DMARC at IONOS as TXT records under Domains & SSL → your domain → DNS → Add Record, using @ in the Host name field for the root domain...
- [Set up SPF, DKIM, and DMARC on Name.com](https://www.schedulerzero.com/setup/email-authentication/name-com.md): Add SPF, DKIM, and DMARC at Name.com by creating TXT records under Manage DNS Records — leave Host blank for SPF on the root domain, use...
- [Set up SPF, DKIM, and DMARC on Porkbun](https://www.schedulerzero.com/setup/email-authentication/porkbun.md): Add SPF, DKIM, and DMARC as TXT records in Porkbun's "Manage DNS Records" editor, leaving the Host field blank (not "@") for root-level records like SPF.
- [Set up SPF, DKIM, and DMARC on DreamHost](https://www.schedulerzero.com/setup/email-authentication/dreamhost.md): Add SPF, DKIM, and DMARC at DreamHost under Websites → Manage Websites → DNS Settings: click Add Record, hover the TXT Record section and click ADD, leave...
- [Set up SPF, DKIM, and DMARC on Wix](https://www.schedulerzero.com/setup/email-authentication/wix.md): Add SPF, DKIM, and DMARC as TXT records in Wix under Domains > Manage DNS Records, in the TXT (Text) section, entering values with no surrounding quotes...
- [Set up SPF, DKIM, and DMARC on Google Workspace](https://www.schedulerzero.com/setup/email-authentication/google-workspace.md): Google Workspace is the email host: you generate the DKIM key inside the Google Admin console, then publish SPF, the generated DKIM TXT, and DMARC at...
- [Set up SPF, DKIM, and DMARC on Microsoft 365](https://www.schedulerzero.com/setup/email-authentication/microsoft-365.md): Microsoft 365 is the email host: it generates DKIM keys in the Defender portal and tells you the exact SPF, DKIM (CNAME), and DMARC records to publish,...

## Email setup (SMTP/IMAP)

- [Gmail / Google Workspace SMTP and IMAP settings](https://www.schedulerzero.com/email-setup/gmail.md): SMTP and IMAP settings for personal Gmail and Google Workspace accounts, including the App Password requirement.
- [Microsoft 365 / Outlook business SMTP and IMAP settings](https://www.schedulerzero.com/email-setup/microsoft-365.md): SMTP and IMAP settings for Microsoft 365 and Exchange Online business mailboxes, including the modern-auth requirement.
- [Outlook.com / Hotmail (consumer) SMTP and IMAP settings](https://www.schedulerzero.com/email-setup/outlook-com.md): SMTP and IMAP settings for free consumer Outlook.com, Hotmail, and Live.com mailboxes.
- [Yahoo Mail SMTP and IMAP settings](https://www.schedulerzero.com/email-setup/yahoo.md): SMTP and IMAP settings for Yahoo Mail, which requires an app password for third-party clients.
- [iCloud Mail SMTP and IMAP settings](https://www.schedulerzero.com/email-setup/icloud.md): SMTP and IMAP settings for iCloud Mail, which mandates two-factor auth and an app-specific password.
- [Zoho Mail SMTP and IMAP settings](https://www.schedulerzero.com/email-setup/zoho-mail.md): SMTP and IMAP settings for Zoho Mail, with notes on regional data centers and app passwords.
- [Fastmail SMTP and IMAP settings](https://www.schedulerzero.com/email-setup/fastmail.md): SMTP and IMAP settings for Fastmail, which uses app passwords for all third-party connections.
- [GoDaddy email (Microsoft 365 and legacy Workspace) SMTP and IMAP settings](https://www.schedulerzero.com/email-setup/godaddy.md): SMTP and IMAP settings for both current GoDaddy email (Microsoft 365) and the legacy Workspace / Professional Email product.
- [Namecheap Private Email SMTP and IMAP settings](https://www.schedulerzero.com/email-setup/namecheap-private-email.md): SMTP and IMAP settings for Namecheap Private Email hosted mailboxes.
- [Hostinger email SMTP and IMAP settings](https://www.schedulerzero.com/email-setup/hostinger.md): SMTP and IMAP settings for Hostinger-hosted email accounts.
- [Proton Mail (via Proton Mail Bridge) SMTP and IMAP settings](https://www.schedulerzero.com/email-setup/proton-mail.md): How to connect Proton Mail over SMTP/IMAP, which requires the paid Proton Mail Bridge app.
- [AOL Mail SMTP and IMAP settings](https://www.schedulerzero.com/email-setup/aol.md): SMTP and IMAP settings for AOL Mail, which requires an app password.
- [Amazon SES (SMTP interface) SMTP and IMAP settings](https://www.schedulerzero.com/email-setup/amazon-ses.md): SMTP relay settings for Amazon SES, including the critical detail that SMTP credentials are not your AWS keys.
- [Twilio SendGrid (SMTP relay) SMTP and IMAP settings](https://www.schedulerzero.com/email-setup/sendgrid.md): SMTP relay settings for SendGrid, where the username is the literal string apikey.
- [Mailgun (SMTP relay) SMTP and IMAP settings](https://www.schedulerzero.com/email-setup/mailgun.md): SMTP relay settings for Mailgun, with per-domain SMTP credentials.
- [Postmark (SMTP relay) SMTP and IMAP settings](https://www.schedulerzero.com/email-setup/postmark.md): SMTP relay settings for Postmark, where the Server API token is used as both username and password.

## Blacklist delisting

- [Spamhaus SBL (Spamhaus Block List) delisting guide](https://www.schedulerzero.com/blacklist/spamhaus-sbl.md): The SBL is a manually curated, real-time database of IP addresses that Spamhaus's investigators have identified as sources or supporters of spam — known...
- [Spamhaus CSS (Composite Snowshoe / Combined Spam Sources) delisting guide](https://www.schedulerzero.com/blacklist/spamhaus-css.md): CSS is an automatically generated subset of the Spamhaus Blocklist (SBL) that lists IP addresses sending low-reputation email — primarily static spam...
- [Spamhaus PBL (Policy Block List) delisting guide](https://www.schedulerzero.com/blacklist/spamhaus-pbl.md): The PBL is a DNSBL listing end-user IP address ranges that should never send email directly to the internet (direct-to-MX) — typically residential,...
- [Spamhaus XBL (Exploits Block List) delisting guide](https://www.schedulerzero.com/blacklist/spamhaus-xbl.md): The XBL is a real-time DNSBL of individual IP addresses observed sending or relaying mail in ways that indicate the machine behind the IP is compromised,...
- [Spamhaus DBL (Domain Block List) delisting guide](https://www.schedulerzero.com/blacklist/spamhaus-dbl.md): The DBL is a domain reputation blocklist published by The Spamhaus Project in domain-DNSBL format. It lists domain names — never IPs — that show signs of...
- [Barracuda Reputation Block List (BRBL) delisting guide](https://www.schedulerzero.com/blacklist/barracuda.md): The BRBL is a free, public, real-time DNS-based blocklist (DNSBL) that Barracuda Networks has maintained since 2008, queried at the zone...
- [SpamCop Blocking List (SCBL) delisting guide](https://www.schedulerzero.com/blacklist/spamcop.md): The SCBL (queried at bl.spamcop.net) is an automated, IP-based DNS blocklist that lists IP addresses that have recently transmitted email reported as spam...
- [SORBS (Spam and Open Relay Blocking System) delisting guide](https://www.schedulerzero.com/blacklist/sorbs.md): SORBS was one of the oldest and largest free DNS-based blocklists (DNSBL), a confederation of 18 distinct DNS zones each targeting a different abuse...
- [UCEPROTECT (Levels 1-3) delisting guide](https://www.schedulerzero.com/blacklist/uceprotect.md): UCEPROTECT-Network is a Switzerland-based DNSBL that detects spam via a cluster of spam-trap servers ("Executive-Members") and publishes three escalating...
- [Invaluement (ivmSIP / ivmSIP/24 / ivmURI) delisting guide](https://www.schedulerzero.com/blacklist/invaluement.md): invaluement is a paid, subscription-only set of DNS blocklists that mail servers and spam filters query to catch spam that bigger lists like Spamhaus...

## Why emails go to spam

- [Why your emails go to spam in Gmail](https://www.schedulerzero.com/why-emails-go-to-spam/gmail.md): Gmail decides spam primarily on per-domain recipient engagement (opens, replies, archives-without-reading, 'mark as spam') scored by a...
- [Why your emails go to spam in Outlook.com (consumer Microsoft)](https://www.schedulerzero.com/why-emails-go-to-spam/outlook-com.md): Outlook.com/Hotmail filters with the SmartScreen ML classifier plus IP/domain reputation from SNDS, and is the most aggressive of the major providers at...
- [Why your emails go to spam in Yahoo Mail](https://www.schedulerzero.com/why-emails-go-to-spam/yahoo.md): Yahoo (and the shared AOL/Verizon Media platform) filters on domain-and-IP reputation driven heavily by its Complaint Feedback Loop, and as a 2024...
- [Why your emails go to spam in Apple Mail (iCloud / Mail Privacy Protection)](https://www.schedulerzero.com/why-emails-go-to-spam/apple-mail.md): Apple Mail leans on iCloud/Proofpoint-style IP-and-domain reputation and authentication, but its defining quirk is Mail Privacy Protection, which...
- [Why your emails go to spam in Microsoft 365 (Exchange Online Protection / Defender)](https://www.schedulerzero.com/why-emails-go-to-spam/microsoft-365.md): Microsoft 365 business mailboxes are filtered by Exchange Online Protection plus Defender, layering tenant/admin anti-spam policies and a...

## Email phrasing

- [What to say instead of "Looking forward to hearing from you"](https://www.schedulerzero.com/email-phrases/looking-forward-to-hearing-from-you.md): It's a passive sign-off that puts the burden on the prospect to figure out the next step. It assumes a reply you haven't earned, adds zero new information, and reads as a default template line, so it gets skimmed past instead of acted on. A real CTA outperforms a hopeful one.
- [What to say instead of "Please find attached"](https://www.schedulerzero.com/email-phrases/please-find-attached.md): It's stiff, dated business-letter language that signals a mail-merge. In cold email, attachments themselves hurt deliverability and trip spam filters, and the phrase tells the reader nothing about why the file is worth opening. It describes the mechanics instead of selling the value.
- [What to say instead of "Gentle reminder"](https://www.schedulerzero.com/email-phrases/gentle-reminder.md): It's passive-aggressive theater: 'gentle' is a hedge that signals you feel awkward chasing, and it reminds them of an email they already ignored without giving a fresh reason to engage. It centers your need (the reminder) instead of their benefit. Good follow-ups add value, they don't re-poke.
- [What to say instead of "I hope this email finds you well"](https://www.schedulerzero.com/email-phrases/i-hope-this-email-finds-you-well.md): It's the single most recognizable cold-email opener, so it instantly flags the message as mass outreach and burns your most valuable real estate — the first line shown in the inbox preview. It's empty filler that delays your hook and gives the reader a reason to delete before you've said anything relevant.
- [What to say instead of "As per our conversation"](https://www.schedulerzero.com/email-phrases/as-per-our-conversation.md): 'As per' is legalistic and cold, and in cold email there often was no real conversation — so it reads as a manufactured rapport that the prospect can't place, breeding suspicion. Even when a chat happened, it's a fussy way to say a simple thing and adds distance instead of warmth.
- [What to say instead of "Thank you in advance"](https://www.schedulerzero.com/email-phrases/thank-you-in-advance.md): It presumes compliance, which can feel manipulative — you're banking a thank-you for something they haven't agreed to do, subtly pressuring them. It also signals your ask is a chore. From a stranger, that entitlement lands worse, because you haven't earned the right to assume the yes.
- [What to say instead of "Circle back"](https://www.schedulerzero.com/email-phrases/circle-back.md): It's worn-out corporate jargon that says 'follow up later' while sounding like you're stalling. It's vague — no when, no why — so it carries no commitment and gives the reader nothing to anticipate. Buzzwords also make outreach feel generic and salesy at exactly the moment you want to feel human.
- [What to say instead of "Touch base"](https://www.schedulerzero.com/email-phrases/touch-base.md): It's empty meeting-speak that asks for time without offering value — 'touch base about what, exactly?' Prospects guard their calendars against vague chats. It centers your desire to talk rather than a reason they'd want to, so it converts poorly into actual booked time.
- [What to say instead of "Per my last email"](https://www.schedulerzero.com/email-phrases/per-my-last-email.md): It's widely read as passive-aggressive code for 'you ignored me' — it scolds the prospect for not replying, which is the fastest way to kill goodwill in cold outreach where you have none banked. It also makes them do the work of finding the old email instead of restating the value cleanly.
- [What to say instead of "Just checking in"](https://www.schedulerzero.com/email-phrases/just-checking-in.md): 'Just' shrinks your own message, and 'checking in' admits you have no new reason to write — it's a follow-up with no value attached, so it's easy to ignore again. It serves your pipeline, not their interests, and trains the prospect to see your name as noise.
- [What to say instead of "Best regards"](https://www.schedulerzero.com/email-phrases/best-regards.md): It is the default sign-off on roughly half the cold emails a prospect receives, so it reads as a form letter. It adds a line of zero information, signals that a template produced the message, and does nothing to make the email feel one-to-one. In a channel where the whole goal is to seem human and specific, a stock valediction quietly confirms you are not.
- [What to say instead of "Sincerely"](https://www.schedulerzero.com/email-phrases/sincerely.md): It belongs to the era of physical business letters and cover letters, so in a cold email it reads as stiff, dated, and impersonal. It instantly raises the formality temperature above how the rest of the message should sound, creating a tonal mismatch that makes the email feel like a mailshot rather than a note from one person to another.
- [What to say instead of "To whom it may concern"](https://www.schedulerzero.com/email-phrases/to-whom-it-may-concern.md): It is a confession that you did zero research and are blasting the same email to a list. Nothing kills cold-email credibility faster: it tells the reader they are one of thousands, the message is not for them specifically, and you could not be bothered to learn their name. Open rates and replies crater because the first line already failed the relevance test.
- [What to say instead of "Quick question"](https://www.schedulerzero.com/email-phrases/quick-question.md): It is one of the most overused cold-email subject lines and openers in existence, so spam filters and trained inboxes flag it on sight. Worse, it almost always lies: what follows is a pitch, not a quick question. The bait-and-switch erodes trust the instant the reader realizes the 'question' is a setup, and many delete before they even open.
- [What to say instead of "Sorry to bother you"](https://www.schedulerzero.com/email-phrases/sorry-to-bother-you.md): It opens from a position of weakness and frames your own email as an imposition, which primes the reader to agree that you are, in fact, a bother. Apologizing for existing signals low status and low confidence, undercuts your value before you state it, and gives the reader explicit permission to dismiss the message. Confident outreach never apologizes for showing up.
- [What to say instead of "Let me know your thoughts"](https://www.schedulerzero.com/email-phrases/let-me-know-your-thoughts.md): It is a vague, low-commitment CTA that asks the reader to do the work of figuring out what to do. 'Thoughts' on what, exactly? It creates decision friction, gives no easy yes-or-no path, and converts far worse than a single specific ask. Open-ended closes feel polite but leave the reader with nothing concrete to respond to, so they respond with nothing.
- [What to say instead of "At your earliest convenience"](https://www.schedulerzero.com/email-phrases/at-your-earliest-convenience.md): It is corporate filler that sounds formal but means nothing actionable. Because it sets no real timeframe, it creates zero urgency and quietly slides to the bottom of the to-do list. The phrase is also a well-worn template tell, marking the email as mass-produced, and its faux-deference reads as stiff rather than respectful.
- [What to say instead of "Thank you for your time"](https://www.schedulerzero.com/email-phrases/thank-you-for-your-time.md): On a cold email it thanks the reader for something they have not yet given, which is presumptuous, and it is such a default closer that it reads as autopilot. It also subtly reinforces the imposition frame, that you took their time, and adds a line of pure politeness with no movement toward the next step. Filler gratitude wastes your most-read real estate: the last line.
- [What to say instead of "I wanted to reach out"](https://www.schedulerzero.com/email-phrases/i-wanted-to-reach-out.md): It is the single most common cold-email opener, which makes it invisible, and it wastes the most valuable line in the email on your intent rather than the reader's interest. It is also self-focused (I wanted) and uses the weak past tense, signaling a template. By the time you finish telling them you wanted to reach out, you have already reached out, so the sentence does no work.
- [What to say instead of "Hope all is well"](https://www.schedulerzero.com/email-phrases/hope-all-is-well.md): It is hollow because you do not know the recipient and they know you do not, so the false familiarity reads as a script. It is among the most pattern-matched opening lines in cold email, triggering instant 'this is a pitch' recognition, and it burns the preview-pane real estate that decides whether the email gets opened at all. Empty warmth from a stranger is worse than no warmth.
- [What to say instead of "Does that make sense"](https://www.schedulerzero.com/email-phrases/does-that-make-sense.md): In writing it lands as condescending, implying the reader might not have followed, and it can read as insecure, as if you are unsure you explained it well. As a CTA it is weak: it invites a yes/no on comprehension rather than a decision or a next step, so even a 'yes makes sense' moves nothing forward. It also signals you may have over-explained in the first place.
- [What to say instead of "Moving forward"](https://www.schedulerzero.com/email-phrases/moving-forward.md): It is corporate-speak filler that adds length without meaning and signals a templated, jargon-heavy register that cold readers tune out. It also presumes a relationship and a 'forward' that does not exist yet on a first touch, getting ahead of a yes you have not earned. In a channel that rewards plain, human language, business cliches like this make the email feel automated.
- [What to say instead of "Would love to pick your brain"](https://www.schedulerzero.com/email-phrases/would-love-to-pick-your-brain.md): It is a tired cliche that experts hear constantly, and it quietly signals a one-sided ask: you want their time and knowledge for free with no clear value back. 'Picking a brain' is vague about the agenda, the duration, and what is in it for them, so busy people decline by default. The forced casualness also masks that you are asking a stranger for a meaningful chunk of time.
- [What to say instead of "Just following up"](https://www.schedulerzero.com/email-phrases/just-following-up.md): It is the laziest follow-up opener: it adds no new value, simply nudges for the reader's sake, and the word 'just' minimizes your own message before the reader even gets to it. A bump that only says 'did you see this' gives the recipient no fresh reason to reply, so it is easy to ignore again. Every follow-up should earn its place with something new, not merely resurface the last one.