I've got a strange problem regarding sendmail. I have a freebsd server running groupware with domain: domain.nl . At the office they have an exchange server also using domain.nl emailaddresses. Email is forwarded to the right server by an external mailserver and local email is handled by the virtusertable.
This is working well for about 100 users on the groupware server but I have one user who is unable to mail to the exchange server. All other users can do that, except this one. he gets an "dsn=5.0.0, stat=Service unavailable" error.
When I make a telnet connection to the exchange server from the groupware server it accepts the mail.