Actually question for you...

You say it goes to different servers of the ISP
Am I correct in understanding that
1. The ISP that the mails go out from IS THE CORRECT ONE
2. The problem is that it uses the wrong server.

If so - try the following
1. nslookup smtp.server.name - see if it resolves to the right IP (perhaps the name table somewhere is screwed up
2. telnet smtp.server.name 587 (587 of course being the port). Check to see if manually you can estabilish a session with the right server


1. I apologize if you are far more technical and have tried all this stuff already. This problem is just eating at me
2. I wonder if I should take this conversation to PMs - maybe I should read the FT rules again.