Overview & Fundamentals

The "engine room" of your email program. This section explains the physical (or cloud) hardware that sends your messages, including MTAs (Mail Transfer Agents), IP addresses, and DNS servers. It's the unseen machinery below deck that gives your ship its power.

14 questions in this topic

What is an ESP (Email Service Provider)? What’s the difference between an ESP and an MTA (Mail Transfer Agent)? How does an ESP send emails? What is a mail relay? What’s the role of DNS in email delivery? What is an SMTP server and how does it work? What are incoming vs outgoing mail servers? What’s the difference between SMTP, IMAP, and POP3? What is a sending pipeline? How do ESPs queue and retry messages? What’s a message ID and how is it generated? How do ESPs track delivery and bounce events? What is shared vs dedicated infrastructure? How does a sending API differ from SMTP submission?

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