-----BEGIN PGP SIGNED MESSAGE----- Hash: SHA1 On 10/8/2014 10:54 AM, Lothar Gesslein wrote: > Hi, > > my postfix has to forward some incoming mails to another SMTP > server not under my control. This SMTP server has filters and > limits that differ from my own, and will reject some mail that > my postfix accepted. When this happens my postfix has to send a > bounce mail back to the original sender. > > Which in most cases means I'm sending backscatter to a forged > address... > > I would like to do the forwarding in the same way the > before-queue content filter feature works. Hold the original > SMTP connection open, open a new SMTP connection to the > destination server and try to deliver the mail, pass any status > code back to the original connection. > > Is this in any way possible? Do you think this is a good idea? > > Best regards, Lothar Gesslein >
The problem is "some incoming mail". Postfix has no method to selectively send some mail to the smtpd_proxy_filter, and pass other mail through (or to a different proxy). Yes, it would be a good idea in this case to selectively proxy messages to the external host, but it's not currently possible. You're stuck in a nasty position. Your best course of action is to get the postmaster at the other server to whitelist you. If you have C programming skills, it might be possible to enhance the existing smtpd_proxy_filter speed_adjust feature to select the proxy based on some message property. I have no idea off-hand how complex that might be. -- Noel Jones -----BEGIN PGP SIGNATURE----- Version: GnuPG v2.0.22 (MingW32) iQEcBAEBAgAGBQJUNWqdAAoJEJGRUHb5Oh6gbrsH/jdTT6xwvfT+9Vj3CXt3wFYY Jf/EQGWCXP1OJp8W3sULqueCacm4e8At0fn2nu4+f9LwL+8VeKHs9xpKSF0o9g35 BpXM5APhgrjl9t97+7Mo64dP8athK47qFRLP2rmPYeDFm0BXIi8YZpH/ZC9TUzp6 q3aFPs6ZlAcasMSnSWI8+3P2LiWEzyVDsHx3b+Ebr9WNMxMAxc1emriqM/Wgri/E SlMXtw11Ht4fvNz5Ztqy9XtXm/69hf1MNBWZlbM0bg3B/ijKbuB8k6/n7OhFbF3R 4/QfXovPHqcJoQ6s6PUH8i555tMASNzIt3TtErz/s9AY+DaFkSdBv4jtzpyDUSI= =VdoM -----END PGP SIGNATURE-----
