Management of the mail server data
14.2. Management of the mail server data#
14.2.1. Management of mail domains#
A mail domain is an common namespace for email addresses, mailing lists and IMAP group folders. Postfix differentiates between the delivery of emails between local and external domains. Delivery to mailboxes defined in the LDAP directory is only conducted for email address from local domains. The name of a mail domain may only be composed of lowercase letters, the figures 0-9, full stops and hyphens.
Several mail domains can be managed with UCS. The managed mail domains do not
need to be the DNS domains of the server - they can be selected at will. The
mail domains registered on a mail server are automatically saved in the
Univention Configuration Registry Variable
To ensure that external senders can also send emails to members of the domain, MX records must be created in the configuration of the authoritative name servers, which designate the UCS server as mail server for the domain. These DNS adjustments are generally performed by an internet provider.
Mail domains are managed in the UMC module Mail with the Mail domain object type.
14.2.2. Assignment of email addresses to users#
A user can be assigned three different types of email addresses:
- Primary email address
The primary email address is used for authentication on Postfix and Dovecot. Primary email addresses must always be unique. Only one primary email address can be configured for every user. It also defines the user’s IMAP mailbox. If a mail home server is assigned to a user (see Distribution of an installation on several mail servers), the IMAP inbox is automatically created by a Univention Directory Listener module. The domain part of the email address must be registered in the UMC module Mail (see Management of mail domains).
- Alternative email addresses
Emails to alternative email addresses are also delivered to the user’s mailbox. As many addresses can be entered as you wish. The alternative email addresses do not have to be unique: if two users have the same email address, they both receive all the emails which are sent to this address. The domain part of the email address must be registered in the UMC module Mail (see Management of mail domains). To receive emails to alternative email addresses, a user must have a primary email address.
When setting the Univention Configuration Registry Variable
true the Alternative email addresses must be unique across the domain.
No other user can have the same alternative address assigned.
- Forward email addresses
If forward email addresses are configured for a user, emails received through the primary or alternative email addresses are forwarded to them. A copy of the messages can optionally be stored in the user’s mailbox. Forward email addresses do not have to be unique and their domain part does not have to be registered via a UMC module.
Email addresses can consist of the following characters: letters
0-9, dots (
.), hyphens (
-) and underscores (
address has to begin with a letter and must include an
@ character. At
least one mail domain must be registered for to be able to assign email
addresses (see Management of mail domains).
Email addresses are managed in the UMC module Users. The primary email address is entered in the General tab in the User account submenu. Alternative email addresses can be entered under .
Once the user account is properly configured, authentication to the mail
stack is possible (
SMTP). Please keep in mind that
after disabling the account or changing the password, the login to the mail
stack is still possible for 5 minutes due to the authentication cache of the
mail stack. To invalidate the authentication cache run
$ doveadm auth cache flush
on the mail server. The expiration time of the authentication cache can be
configured on the mail server with the Univention Configuration Registry Variable
14.2.3. Management of mailing lists#
Mailing lists are used to exchange emails in closed groups. Each mailing list has its own email address. If an email is sent to this address, it is received by all the members of the mailing list.
Mail domains are managed in the UMC module Mail with the Mailing list object type. A name of your choice can be entered for the mailing list under Name; the entry of a Description is optional. The email address of the mailing list should be entered as the Mail address. The domain part of the address needs to be the same as one of the managed mail domains. As many addresses as necessary can be entered under Members. In contrast to mail groups (see Management of mail groups), external email addresses can also be added here. The mailing list is available immediately after its creation.
By default everyone can write to the mailing list. To prevent misuse, there is
the possibility of restricting the circle of people who can send mails. To do
so, the Univention Configuration Registry Variable
mail/postfix/policy/listfilter on the mail server
must be set to
yes and Postfix restarted. Users that are allowed to send
emails to the list and Groups that are allowed to send emails to the list
can be specified under Advanced settings. If a field is set here, only
authorized users/groups are allowed to send mails.
14.2.4. Management of mail groups#
There is the possibility of creating a mail group: This is where an email address is assigned to a group of users. Emails to this address are delivered to the primary email address of each of the group members.
Mail groups are managed in the UMC module Groups (see Group management).
The email address of the mail group is specified in the mail address input field under Advanced settings. The domain part of the address must be the same as one of the managed mail domains.
By default everyone can write to the mail group. To prevent misuse, there is the
possibility of restricting the circle of people who can send mails. To do so,
the Univention Configuration Registry Variable
mail/postfix/policy/listfilter on the mail server must
be set to
yes and Postfix restarted.
Users that are allowed to send emails to the group and Groups that are allowed to send emails to the group can be specified under Advanced settings. If a field is set here, only authorized users/groups are allowed to send mails.
14.2.6. Mail quota#
The size of the users’ mailboxes can be restricted via the mail quota. When this is attained, no further emails can be accepted for the mailbox by the mail server until the user deletes old mails from their account.
The limit is specified in megabytes in the Mail quota field under
means that no limit is set. The multi edit mode of UMC modules can be used to
assign a quota to multiple users at one time, see
The user can be warned once a specified portion of the mailbox is attained and then receives a message that their available storage space is almost full. The administrator can enter the threshold in percent and the messages subject and text:
The threshold for when the warning message should be issued can be configured in the Univention Configuration Registry Variable
mail/dovecot/quota/warning/text, for example
PERCENTmust be a number between 0 and 100 without the percent sign.
TEXTwill be the content of the email. If the value
TEXTcontains the string
$PERCENT, it will be replaced in the email with the value of the limit that has been exceeded.
The value of the Univention Configuration Registry Variable
mail/dovecot/quota/warning/subjectwill be used for the subject of the email.
When the mail server package is installed, a subject and two warning messages are automatically configured:
mail/dovecot/quota/warning/subjectis set to
mail/dovecot/quota/warning/text/80is set to
Your mailbox has filled up to over $PERCENT%.
mail/dovecot/quota/warning/text/95is set to
Attention: Your mailbox has already filled up to over $PERCENT%. Please delete some messages or contact the administrator.