We have issue with outgoing email for one of our distribution groups that includes contacts(non-company email addresses).
Here is an error message:
GROUP_NAME on 23/03/2011 14:20
There was a SMTP communication problem with the recipient’s email server. Please contact your system administrator.
The error comes when customers send email to distribution group email address and our exchange then fire email to all group members.
Mails to members with company email address delivered fine.
Our exchange server configured to send all outgoing emails to ISP SMTP server.