Hello, I am in a case, where I need to configure a postfix daemon for acting as an SMTP server, where some spam-filtering and some anti-virus would run in parallel in the box. This would be a help, for a local ISP, to control spam relayed outside from his own network and thus avoiding IPs to get blacklisted, etc. Now my problem. The users can use the SMTP server directly, thus if they select mysmtp.mynetwork.com everything is okay.
Now, we do suppose that a few users do have a valid subscription for an SMTP server, outside our network, say theirsmtp.theirnetwork.com. That foreign server uses SMTP auth as well. Obviously, redirecting that traffic first to our proxy, results in complete e-mail delivery failure. Is any way to handle this? Preferable methods. a) Our SMTP proxy, talks with the foreign SMTP and sends the e-mail accordingly. b) Our SMTP proxy, just forwards the commands, without checking the e-mail for spam/virus (not vey wise, but if there's no other solution, is part of the foreign server's responsibility to do these checks) c) Our SMTP proxy, just sends the e-mail directly to the recipient after checking it, without ever talking to the foreign SMTP server (it can cause problems with DKIM and SPF domains, but in any case, it may be helpful). What I need, is some configuration instructions about how to achive such a functionality. Best Regards N. Sideris
