On Sun, 2007-04-01 at 17:00 +0200, Thomas Hochstein wrote: > Bob Johnson schrieb: > > > I think the sending system should have a timeout longer than 60 seconds, > > It is *required* to have a much longer timeout.
There's many things that are required according to RFCs that are impractical on the modern day Internet. The mandated 10 minute timeout is one of these -- if you run a web server, you then quickly end up with tens of thousands processes in FIN_WAIT status, because of clients who don't play nice and just go away (which saves the *client* a millisecond). Similar for mail, where spammers in particular don't play nice, and may not bother about niceties like QUIT and a TCP negotiated FIN/FIN+ACK/ACK sequence, but just drop the connection to save a few milliseconds. To hell with the server; the spammer saving time is much more important to the spammer. So no, for several years now, the RFC recommended timeout values have been obsolete. > > but even so, this is a bug in Exim. > > No, it isn't. It is a bug in the remote installation, and perhaps a > poor configuration of the local SpamAssassin, but not an Exim-bug. Or the infamous Cisco PIX firewall bug which causes a timeout (and dupe deliveries) if the final <CR><LF>.<CR><LF> isn't all part of one TCP/IP packet due to an unlucky combination of the email size and the max MTU size between sender and recipient. Or the similarly infamous PIX firewall problem if someone is using PIX Mailguard in front of a server that does ESMTP -- then the sending MTA will never get a 2xx or 5xx return on the ESMTP commands (IIRC, PIX returns "OK" after filtering, instead of "500 something" which it should), and eventually timeout unless the sending MTA sends a CR every now and then when inactive (many do, just because of this). In that case, there shouldn't be dupes, though. In either case, the correct fix (IMHO) is to thump the PIX device repeatedly over the head of whoever decided to buy it, while chanting "do not ever buy black box security devices". Regards, -- *Art -- ## List details at http://www.exim.org/mailman/listinfo/exim-users ## Exim details at http://www.exim.org/ ## Please use the Wiki with this list - http://www.exim.org/eximwiki/
