Comment 62 for bug 1899485

(In reply to gergilar from comment #57)
> I have removed all this:
>
> [...]
> user_pref("ldap_2.servers.eds.description", "EDS Address Book Bootstrapper");
> user_pref("ldap_2.servers.eds.dirType", 3);
> user_pref("ldap_2.servers.eds.filename", "eds.mab");
> user_pref("ldap_2.servers.eds.position", 1);
> user_pref("ldap_2.servers.eds.uri", "moz-abedsdirectory://");

I think this is the key. Relevant information:

http://kb.mozillazine.org/Sharing_address_books#EDS
https://launchpad.net/thunderbird-eds-extension

And, this bug:

sending mail impossible in thunderbird, when plugin is installed and activated
https://bugs.launchpad.net/thunderbird-eds-extension/+bug/1326766

Do you have that add-on installed and enabled?