Hosting mail on 10.5 server with a 10.7/10.8 Open Directory

In one of my deployments, an emotional connection to an ageing Xserve G5 has meant that mail services continue to be hosted on 10.5 server. With almost all stock packages ripped out replaced with up to date or custom variants (big shoutout to Topicdesk!), everything works very smoothly, and has done for many years.

With the advent of Lion server however, directory and collaboration services were moved to a new Mac mini running 10.7, and as the OD was old and messy, it was entirely rebuilt from scratch, with manual entry of users and groups in Server.app. As 10.5 mail services are keyed off a users shortname and not the GUID, mailboxes carried across nicely when the Xserve was bound to the new 10.7 directory.

An error was encountered however, when users attempted an IMAP login:

Mar 28 12:23:45 mail imaps[27929]: badlogin from: jeddambp [192.168.16.23]. CRAM-MD5 user: johnsmith. mail is not enabled for this user

Mail SACLs were set correctly for users, but the error persisted.

10.7, having omitted the Mail tab from Workgroup Manager, maintains no way to set individual user quotas, or set a user’s mail server from within the GUI. In doing so, the MailAttribute attribute is not created in a 10.7 directory by default, unless mail services are hosted on the same machine.

Mail service on the 10.5 server was therefore restored by re-defining a MailAttribute based on the following plist for each user you want a mailbox for:

<?xml version="1.0" encoding="UTF-8"?>
<dict>
<key>kAPOPRequired</key>
<string>APOPNotRequired</string>
<key>kAltMailStoreLoc</key>
<string></string>
<key>kAttributeVersion</key>
<string>Apple Mail 1.0</string>
<key>kAutoForwardValue</key>
<string></string>
<key>kIMAPLoginState</key>
<string>IMAPAllowed</string>
<key>kMailAccountLocation</key>
<string>your.server.hostname</string>
<key>kMailAccountState</key>
<string>Enabled</string>
<key>kPOP3LoginState</key>
<string>POP3Deny</string>
<key>kUserDiskQuota</key>
<string>0</string>
</dict>

You will need to define kMailAccountLocation as your mail server’s hostname, and have the ability to set individual user quotas for users with the kUserDiskQuota key.

Adding this attribute is fairly easy in Directory Utility by navigating to the Directory Editor Tab, and clicking the plus button in the horizontal divider. You could also do this for a larger number of users by using dscl. There is good article here that has some examples of doing similar things.