I believe you want to set the 'relayhost' parameter in
/etc/postfix/main.cf. I don't know what you need to do regarding
providing authentication to that server.
Addressing another comment, an increasing number of sites blindly reject
all email originating at consumer IP addresses. It's harsh, but for every
message from a technically competent user with his own domain there's
easily 1000+ from hijacked PCs. (This is why sysadmins are not entirely
joking when they argue for the death penalty for spammers.)
Worse, some ISPs have started filtering outbound port 25 traffic. Same
argument -- they're cutting down on complaints (and bandwidth) by blocking
traffic that's 99.9+% illegitimate. Businesses should always block
outbound port 25 traffic from all but their authorized mail servers,
although few actually do.
You can forward mail through your ISP, but spam strikes again. Some ISPs
have started rewriting headers to show the 'correct' sender. E.g., while
you wanted to send mail from "bsmith@...
" they can't distinguish
that from "customer.service@...
" so they rewrite all headers as
My approach has been running my own virtual hosted server at tummy.com.
It's only $25/month and gets me around all of these hassles. It may not
be cost-effective for you -- I need to eat my own dog food if I claim to
be a competent Linux sysadmin.
> Thanks but I can "get" emails down to the slug but I don't know how to
> configure Postfix to send them to my ISP.
> Any ideas ..?