Hi,
As Zoran pointed out, you can use tcpserver to specify which IP addresses
are allowed to relay - works fine, unless the customers have dynamic IPs. If
the latter should be the case, consider using SMTP-AUTH or POP after SMTP,
you can find various implementations on http://www.qmail.org ...
I don't think that there is any reason to switch from qmail to postfix to
solve your problem. If qmail is configured correctly and if the hostmaster
knows what he does, qmail is very stable and secure. If the hostmaster does
not, sooner or later you'll have security problems, no matter which mailer
you are running. I *don't* say qmail is better than postfix or vice versa,
we are using both, so please, no flame-wars :-)
Best regards
Reto Inversini
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