I hadn't noticed this until now and it's an interesting problem with Postfix... I have a few sites on my system. Two of the sites have a user name of "jim". So that makes user names like web1_jim and web2_jim. The interesting part is all mail for web2_jim is going to web1_jim. Now, what I THINK is happening is Postfix isn't doing a complete domain name check on the user names. I say this because both domain names are identical in size and start with the same word. Something like mashersock.com and masherhost.com. So you'd have [email protected] web1_jim [email protected] web2_jim So, like I said it seems to be matching the first "[email protected] Any ideas?