KB885: SMTP Error: 553: Sorry, that domain is not in my list of allowed rcpthosts
SUMMARY: When sending mail to a remote server, you may receive a message similar to the following:
553: Sorry, that domain isn't in my list of allowed rcpthosts
RESOLUTION: This error message indicates that the remote server has rejected your message due to your host not being on a list of servers able to send the destination server mail. This error can also indicate that your e-mail address or server is listed on a DNS blacklist. You will need to contact the remote server administrator for assistance with this issue. This error has nothing to do with Groupware Server 6.0, it is a problem with the remote host.