Send Format LDAP
Send Format LDAP is an add-on for Mozilla Thunderbird 2 which gets supported email formats (text/HTML) by the recipients from LDAP directories. By default, Thunderbird looks for supported email formats for the recipients only in local address books, not in LDAP directories.
This feature is based on LDAP settings for address autocompletion (global or account-specific).
It can be used with Multi-LDAP add-on in order to check several directories simultaneously.
The property defining the boolean LDAP attribute to look for is a standard Thunderbird property named ldap_2.servers.default.attrmap.PreferMailFormat. By default, this property has the value mozillaUseHtmlMail,xmozillausehtmlmail. These attributes are defined by the Mozilla LDAP Address Book schema. So, it is possible to configure the attributes to look for by defining values of this property.
For the standard mechanism, you can refer to the handling of mail content types by Thunderbird.