A common feature with mail environments is to use distribution groups that you could add and remove group members from. This is fairly common among organizations. For example, one might have hq@example.net and a list of members stored in LDAP. I wanted to have the ability to use mail distribution groups with my OpenLDAP infrastructure. LDAP group members could then easily be removed or added using ldapmodify or Apache Directory Studio.

Postfix

First, we need to tell Postfix about our LDAP distribution group config.

  1. Open /etc/postfix/main.cf
  2. Edit the virtual_alias_maps line and put ldap:/etc/postfix/ldap/ldap-groups.cf after the aliases definition.
    virtual_alias_maps = ldap:/etc/postfix/ldap/ldap-aliases.cf,ldap:/etc/postfix/ldap/ldap-groups.cf

    Since the LDAP server is local I do not need TLS in ldap-groups.cf. The following is sufficient.

ldap-groups.cf

server_host = ldap://localhost
search_base = ou=Groups,ou=Mail,dc=example,dc=net
version = 3
bind = no
query_filter = mail=%s
result_attribute = mailGroupMember

The group attrributes can be loaded using postfix-book schema

An LDAP mail distribution group could look like this.

dn: mail=hq@example.email,ou=Groups,ou=Mail,dc=example,dc=net
objectClass: top
objectClass: organizationalPerson
objectClass: PostfixBookMailAccount
mail: hq@example.email
mailEnabled: TRUE
mailUidNumber: 5000
mailGidNumber: 5000
cn: hq
sn: group
description: hq@example.email distribution group
mailGroupMember: user1@example.email
mailGroupMember: user2@example.email
mailGroupMember: user3@example.email
mailGroupMember: user4@example.email
mailGroupMember: user5@example.email
mailGroupMember: user6@example.email

So now, when an email is sent to hq@example.email that email will land in every group member's Inbox. Each group member will be defined by the mailGroupMember attribute.

Once you have this configured it is a good idea to tail the logs and send a test mail to the group. If everything is setup correctly the mail logs will show the email delivered to all group members.

Originally I researched a bit to get ideas and started writing a tool to add email user accounts in LDAP. That eventualy manfested into another separate script which creates email distribution groups. While one could just as easily use phpLDAPadmin, Apache Directory Studio and others by giving a .ldif file - I wanted something with less overhead, so I began to write a script that was specific to only adding LDAP email users and distribution groups interactively. In a nutshell these scripts use an LDIF template to help create the email user account or email distribution group on the fly. There is no need to ever manually edit a .ldif file since all you do is give some preliminary info and be done with it.

Email Users

Invoking the script as root or sudo will run through the following.

# ./add_ldap_mail_user.sh
First Name: Jane
Last Name: Doe
User Name [uid]: jane.doe

==================
 MAIL DOMAIN MENU
==================
domain1.com
domain2.com
domain3.com
domain4.email
domain5.email
domain6.email
domain7.me
domain8.net

Enter the domain to use for the mail account: domain4.email
creating mail account on domain4.email
adding new entry "uid=jane.doe,ou=Mail,dc=example,dc=com"

modifying entry "cn=vmail,ou=Groups,c=example,dc=com"

Successfully added Mail account

We can see our new email user gets added to an LDAP group. Note that this is a standard groupOfNames group and not an email distribution group.

Email Welcome Message

When an LDAP email user is added, a welcome email message is sent to the newly created user's Inbox. A default html and plain text email template are available to use. It is also easy to have your own customizable email templates.

Email Distribution Groups

Invoking the script will run through the following to create an email distribution group.

# ./add_ldap_mail_group.sh
Email Group Name: engineers

==================
 MAIL DOMAIN MENU
==================
domain1.com
domain2.com
domain3.com
domain4.email
domain5.email
domain6.email
domain7.me
domain8.net

Enter the domain to use for the mail group: domain4.email
creating mail group on domain4.email
adding new entry "cn=engineers,ou=Groups,ou=Mail,dc=example,dc=com"

Successfully added Email Distribution Group

Group members can be added using the mailGroupMember attribute provided by postfix-book.schema, respectively.

Contact

Comments, improvements, PRs and everything else should be directed on GitHub.

PRs welcome.