Is it possible to have vpopmail add the client's domain name and IP to the open-smtp file so it will only allow relay to that domain name and IP?
You'd have to modify vchkpw.c so it added an environment variable to the open-smtp entry and qmail-smtpd.c so it would check that variable and error out if necessary.
If you're running Courier-IMAP, you'd have to modify it's authvchkpw module as well.
You'll run into problems though, if two people using different domain names connect through the same IP (through a firewall, perhaps).
I think that a more useful patch (but still not one that I would use or one that should be in place by default) would be an option to limit MAIL FROM (sender email) to the one used in SMTP AUTH. Or even just the patch to make sure that the sender address from a RELAYCLIENT is one of the domains you're hosting.
-- Tom Collins - [EMAIL PROTECTED] QmailAdmin: http://qmailadmin.sf.net/ Vpopmail: http://vpopmail.sf.net/ Info on the Sniffter hand-held Network Tester: http://sniffter.com/