I have a RedHat 7 server set up with Sendmail. I have a few people that connect to this on a daily basis. I have had to change the server timeout setting on some of these computers to get the mail to go through. I have been fighting this for a few weeks now and I have narrowed it down to a few possible causes. Some people are using SP2 on WinXP, some are using Norton AV 2005, and one is using NAT on a crappy router. I use SP2 but don't have this issue, but others do, so I can't say for certainty that that is part of it or not. I have tried disabling firewalls and such to no avail. I've searched through several forums (inc this one) but haven't seen anyone else with this issue, which makes me think it may be a setup issue on my mail server. Anyone have any idea what in the setup of this box would cause this?