Infrastructure
What is Mail Transfer Agent (MTA)?
The server software that routes and delivers email between domains using SMTP.
A Mail Transfer Agent is the software responsible for sending, receiving, and relaying email over SMTP between mail servers, with Postfix and Exim being common examples alongside the infrastructure behind providers like Google Workspace. The MTA handles message queuing, retries on temporary failures, connection throttling, and the delivery negotiation (including TLS) with the recipient's inbound server. Its behavior on every connection is observable to receivers and feeds their filtering decisions.
Why it matters for cold email
In cold email the sending MTA's configuration and IP behavior, such as retry logic, connection limits, TLS, and reverse DNS, directly shape how receivers judge you, so a well-behaved MTA is the foundation of reaching the inbox at volume.
Related terms
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