cyrus cuts away the realm on the admin user

[Marten Lehmann]

Hello,

I want to authenticate the admin user against ldap as all other users in 
our setup. Our admin user is something like admin at server whereby 
"server" is set as defaultdomain in imapd.conf.

When I login with a usual account it looks like this:

Mar  5 22:09:58 vmx saslauthd[27772]: do_auth         : auth failure: 
[user=test] [service=imap] [realm=test.com] [mech=ldap] [reason=Unknown]

But when I'm using the admin-account (which I need to do with cyradm), 
then the realm disappears, not matter if I'm using admin at server as the 
login or just "admin":

Mar  5 22:09:43 vmx saslauthd[27771]: do_auth         : auth failure: 
[user=admin] [service=imap] [realm=] [mech=ldap] [reason=Unknown]

But without the realm the verification against ldap fails. How can I 
tell cyrus to pass the realm?

Regards
Marten