This took me a couple of hours to solve:

We're using LDAP to authenticate users against an ActiveDirectory. Some users authenticated well while others did not at all.

I discovered that the users which did not authenticate had an backslash '\' in their distinguishedName attribute. This is always the case if the users name is defined as "surname, givenName" (like "Doe, John", as is the standard in our organization. Windows automagically escapes the comma to "CN=Doe\, John,OU=..." in the distinguishedName attribute.

Once I renamed the user to 'givenName surname' (e.g., "John Doe"), authentication and logon to the SOGo web interface worked well.

I think this should be fixed in SOGo.