Thunderbird can connect to an LDAP server and autocomplete email addresses as you type, but it needs some adjustment for some LDAP servers. One of the LDAP servers that I use regularly returns email addresses like this in the thunderbird interface:

username <firstname.lastname@domain.tld>

The email address looks fine, but I’d much rather have the person’s full name instead of the username. Here’s what I’m looking for:

Firstname Lastname <firstname.lastname@domain.tld>

In older Thunderbird versions, setting ldap_2.servers.SERVER_NAME.autoComplete.nameFormat to displayName was enough. However, this option isn’t used in recent versions of Thunderbird.

Digging in

After a fair amount of searching the Thunderbird source code with awk, I found a mention of DisplayName in nsAbLDAPAutoCompleteSearch.js that looked promising:

// Create a minimal map just for the display name and primary email.
      this._attributes =
        this._book.attributeMap.getAttributeList("DisplayName", {}), true);
        this._book.attributeMap.getAttributeList("PrimaryEmail", {}), true);

Something is unusual here. The LDAP field is called displayName, but this attribute is called DisplayName (note the capitalization of the D). Just before that line, I see a lookup in an attributes map of some sort. There may be a configuration option that is called DisplayName.

In Thunderbird, I selected Edit > Preferences. I clicked the Advanced tab and then Config Editor. A quick search for DisplayName revealed an interesting configuration option:

ldap_2.servers.default.attrmap.DisplayName: cn,commonname

Fixing it

That’s the problem! This needs to map to displayName in my case, and not cn,commonname (which returns a user’s username). There are two different ways to fix this:

# Change it for just one LDAP server
ldap_2.servers.SERVER_NAME.attrmap.DisplayName: displayName
# Change it for all LDAP servers by default (careful)
ldap_2.servers.default.attrmap.DisplayName: displayName

After making the change, quit Thunderbird and relaunch it. Compose a new email and start typing in the email address field. The user’s first and last name should appear!