Good morning.

I was just reading https://wiki.dovecot.org/AuthDatabase/LDAP/PasswordLookups and found the following statement

When using LDA and static userdb, deliver can check if destination user exists. With auth binds this check isn't possible.

Is this still relevant? Is there a workaround? It seems like using dovecots lmtp in an active directory environment is not possible, is this correct?

You cannot check user existence with auth binds because auth bind requires user credentials.

This is why I suggested you use a "service user" in LDAP to perform the database lookups instead of auth binds. You can still authenticate your users using kerberos.

Aki