UCS 2.4 - Univention

12.3 Setting up the mail server
To assign a user an e-mail address, his primary e-mail address must be entered in Primary e-mail ad-
dress of the the Mail tab of a user object in Univention Directory Manager. This is used for authentication
on the mail server. Additionally any number of further addresses under which the user should be reachable
can be entered in the Alternative e-mail addresses field. The e-mails sent to the entered user addresses
are all delivered to the same inbox. If two users have the same alternative e-mail address, they both
receive all the e-mails which are sent to this address. Primary e-mail addresses on the other hand must
always be unique.
Postfix differentiates between the delivery of e-mails between local and external domains. Delivery to
mailboxes defined in the LDAP directory is only conducted for e-mail address from local domains. The
DNS domain of the mail server is preset for this. If e-mail addresses should be assigned to local mailboxes
which are not from the server’s domain, a list of the domains to be used can be defined using the Univention
Configuration Registry variable mail/hosteddomains. Example:
univention-config-registry set mail/hosteddomains="mydomain.com \
myotherdomain.com subdomain.mydomain.com"
In this it must be noted that the otherwise preset domains of the server must be a component of this list to
process e-mails from the local domain. Then the command
postmap /etc/postfix/transport
must be executed to adopt the changes via Postfix.
For incoming e-mails Postfix performs a validity test in the form of a search of the LDAP directory for
domains from the thus defined field of responsibility. That means that e-mails are only accepted for e-mail
addresses defined in the LDAP directory or via an alias.
Following the optional filtering for spam and viruses, the received e-mails are forwarded to the local
POP/IMAP server Cyrus.
E-Mails to foreign domains are sent directly to the responsible server as standard, which is resolved
via MX records. If the output should be taken over by a relay host, e.g., the Internet provider, the fully
qualified domain name of the relay host must be entered in the Univention Configuration Registry variable
mail/relayhost.
If authentication is necessary on the relay host for sending, the Univention Configuration Registry variable
mail/relayauth must be set to yes and the /etc/postfix/smtp_auth file edited. The relay host,
user name and password must be saved in this file in one line.
:
The following command must then be executed for this file to adopt the changes via Postfix.
postmap /etc/postfix/smtp_auth
The Univention Configuration Registry variable mail/messagesizelimit can be used to set the maxi-
mum size in bytes for incoming and outgoing e-mails. The preset maximum size is 10240000 bytes. If the
value is configured to 0 the limit is effectively removed.
After modifying configuration settings Postfix must be restarted to ensure correct functioning in accordance
with the settings. This is done with:
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