Hi all. This is sort of like a follow-up on a problem I have with the same mailserver but now I have some new informations that could probably help someone an idea on what is going on. To recap, someone from Company A is complaining that they have not been receiving any emails sent from our mailserver. They have also said that we have been ignoring emails sent by them to our staff. Now, they are saying that they are receiving returned emails that says that their mailsever have encountered errors sending emails to our mailserver. I have checked our mail log and don't actually see any errors. Is there any way for me to find out what is going on and sort of investigate this further using any tools or something to make sure that our mailserver are working fine. At this point, we are just pointing blame to each other's mailserver. A different question. If we were to create a new mailserver, is there an easy way to migrate all the users and emails from our old mailserver to the new mailserver? FYI, the current mailserver is setup using the guide in this site, ie. "Virtual Users With Postfix, PostfixAdmin, Courier, Mailscanner, ClamAV On CentOS". However, the current mailserver is running on FC5.