Zimbra Collaboration Suite 7.0
Zimbra Collaboration Suite 7.0
Administrator's Guide
Open Source Edition


Zimbra MTA

Zimbra MTA
The Zimbra MTA (Mail Transfer Agent) receives mail via SMTP and routes each message, using Local Mail Transfer Protocol (LMTP), to the appropriate Zimbra mailbox server.
Topics in this chapter include: 
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The Zimbra MTA server includes the following programs:
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SpamAssassin, a mail filter that attempts to identify unsolicited commercial email (spam) with learned data stored in the default Berkeley DB database or an alternative MySQL database.
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Milter servers filter applications that can be configured to filter email ReciptTo content for alias domains and to filter restricted sender addresses for distribution lists.
In the Zimbra Collaboration Suite configuration, mail transfer and delivery are distinct functions. Postfix primarily acts as a MTA and the Zimbra mail server acts as a Mail Delivery Agent (MDA).
MTA configuration is stored in LDAP and a configuration script automatically polls the LDAP directory every two minutes for modifications, and updates the Postfix configuration files with the changes.