I've recently installed a hub (LinkSys) that also doubles as a router, gateway, firewall, and wireless access. With my PC that is connected via one of the wired connections, I can no longer send email out. I am using Outlook XP and Windows XP Pro SP1. Other services that work perfectly fine:
- web browsing
- FTP
- email sent programatically from VFP using CDO
- posts to newsgroups

The response is below if I send to any email address.

******
Your message did not reach some or all of the intended recipients.

Subject: test
Sent: 2/8/2003 10:58 AM

The following recipient(s) could not be reached:

'edelay@vanhosp.bc.ca' on 2/8/2003 10:58 AM
550 , Recipient unknown
******

If I unplug the hub and connect directly to my DSL modem, the email is sent fine.