EMZETT.Mail Server
In short: A server that receives, sends, and/or holds emails for users.
In more detail: Depending on the task, a distinction is made between mail transfer agents (MTA, sending/forwarding via SMTP) and mail delivery/access services (retrieval via IMAP/POP3). Which mail server is responsible for a domain is defined via the MX record in DNS.
In Depth
In practice, “mail server” usually covers several separate roles, which can also be handled by different systems:
- MTA (Mail Transfer Agent): receives mail via SMTP and forwards it to the next responsible server (e.g. Postfix, Exim).
- MDA (Mail Delivery Agent): finally places incoming mail into the recipient’s mailbox.
- MAA (Mail Access/Retrieval): makes mail available for retrieval by mail clients via IMAP or POP3.
Many companies no longer run their own mail server, but use hosted services (Google Workspace, Microsoft 365, or specialised transactional mail providers like Resend for automatically sent mail like order confirmations). The main reason for this is the “reputation” of a sending mail IP: large providers invest considerably in spam avoidance and deliverability, while a freshly set-up own mail-server IP is often initially treated with suspicion by spam filters, until it has “earned” a good reputation over time.