Microsoft 365 SMTP and IMAP settings
SMTP and IMAP settings for Microsoft 365 and Exchange Online business mailboxes, including the modern-auth requirement.
Outgoing mail (SMTP)
| SMTP server | smtp.office365.com |
|---|---|
| Port | 587 (STARTTLS) |
| Username | Your full Microsoft 365 email address |
| Password | See authentication note below |
Incoming mail (IMAP)
| IMAP server | outlook.office365.com |
|---|---|
| Port | 993 |
| Security | SSL/TLS |
Authentication
Microsoft has deprecated basic SMTP AUTH. Most tenants now require OAuth 2.0 / modern authentication, and SMTP AUTH may need to be explicitly enabled per-mailbox by an admin in the Microsoft 365 admin center.
Sending limits
Exchange Online limits are roughly 30 messages/minute and 10,000 recipients/day per mailbox.
How to set up Microsoft 365 in your email tool
- Open your email client or sending tool and add a new account.
- For incoming mail, choose IMAP and enter server outlook.office365.com, port 993 (SSL/TLS).
- For outgoing mail, enter the SMTP server smtp.office365.com on port 587 (STARTTLS).
- Set the username to your full microsoft 365 email address, and use the password described in the authentication note above.
- Save the account and send a test email to confirm it works.
Connecting is the easy part. Landing in the inbox is not.
Once Microsoft 365 is connected you can send, but whether your cold email reaches the inbox depends on SPF, DKIM, and DMARC authentication, your sender reputation, and proper domain warmup. Scheduler Zero handles warmup and deliverability so your emails actually land.