My dedicated server inexplicably got its default gateway changed a couple days ago (I suspect a goof-up by the provider), so it wasn't network-accessible. Once the techs changed it back, I got everything working again (I thought), but now I've found out that Postfix times-out whenever it tries to deliver mail to any address for which the box itself is not the final destination. Manually talking to the indicated destination servers on port 25 is successful. Changing the connection timeout seems to make the process take somewhat longer but does not improve anything. Some packet sniffing I did appeared to indicate that postfix opens a dozen or more connections within a second or two of each other to deliver a single piece of mail. On each connection it seems to send first one SYN packet 60b long, then another a second or so later. It gets no response. That's the only odd-looking thing I can find, but I never did packet sniffing when everything was working, so I don't know what it would have looked like then.
