But how about this: in addition to MX hosts, every domain also has one or more MO (mail originator) hosts. Mail servers then get to check the address of the SMTP server they're talking to against the DNS records for the domain in the sender's address. Then customers who use an email address under their ISP's domain have to use the ISP's relay, while people with their own (sub) domain get to use their own.
I travel around. I read my email by POP3/IMAP, I use local ISP's SMTP server for outgoing - surely that means I can't use my own domain for email? Simon -- Simon Lockhart | Tel: +44 (0)1628 407720 (x37720) | Si fractum Technology Manager | Fax: +44 (0)1628 407701 (x37701) | non sit, noli BBC Internet Operations | Email: Simon.Lockhart@bbc.co.uk | id reficere BBC Technology, Maiden House, Vanwall Road, Maidenhead. SL6 4UB. UK