Date: Mon, 22 Jun 2020 17:13:02 +0100 From: Mike Clarke <jmc-freebsd2@milibyte.co.uk> To: freebsd-questions@freebsd.org Subject: Re: Exim - retry time not reached for any host Message-ID: <1854884.R0FQcr2YjX@curlew> In-Reply-To: <f9413c03-db27-52de-6a1d-48c2d55df04f@smokepit.net> References: <2534646.NQNxk83B2J@curlew> <2063278.3V7qYkmoPJ@curlew> <f9413c03-db27-52de-6a1d-48c2d55df04f@smokepit.net>
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On Monday, 22 June 2020 11:27:30 BST Daniel Lysfjord via freebsd-questions wrote: > In your route_list, you have mail3.gridhost.co.uk, not that it should > matter, For some reason the service provider quotes mail3.gridhost.co.uk in their email setup instructions despite it advertising itself as mail.gridhost.co.uk. > but you could try changing that to mail.gridhost.co.uk (or, > possibly 95.142.156.18). I have replaced mail3.gridhost.co.uk with 95.142.156.18 and tried another test while monitoring with wireshark. The output showed only 3 packets being transmitted: No. Time Source Destination Protocol Length Info 1 0 192.168.1.13 95.142.156.18 TCP 74 25272 > 465 [SYN] Seq=0 Win=65535 Len=0 MSS=1460 WS=64 SACK_PERM=1 TSval=3438884996 TSecr=0 2 0.021859743 95.142.156.18 192.168.1.13 TCP 74 465 > 25272 [SYN, ACK] Seq=0 Ack=1 Win=43440 Len=0 MSS=1452 SACK_PERM=1 TSval=4269392837 TSecr=3438884996 WS=2048 3 0.021872274 192.168.1.13 95.142.156.18 TCP 54 25272 > 465 [RST] Seq=1 Win=0 Len=0 And that was all there was, absolutely nothing after the RST packet. I then tried your earlier suggestion of 'exim -Rf @gmail.com' and much to my surprise the email was sent No. Time Source Destination Protocol Length Info 1 0.000000000 192.168.1.13 95.142.156.18 TCP 74 12424 → 465 [SYN] Seq=0 Win=65535 Len=0 MSS=1460 WS=64 SACK_PERM=1 TSval=2845252007 TSecr=0 2 0.021910067 95.142.156.18 192.168.1.13 TCP 74 465 → 12424 [SYN, ACK] Seq=0 Ack=1 Win=43440 Len=0 MSS=1452 SACK_PERM=1 TSval=4253626233 TSecr=2845252007 WS=2048 3 0.021923963 192.168.1.13 95.142.156.18 TCP 66 12424 → 465 [ACK] Seq=1 Ack=1 Win=66752 Len=0 TSval=2845252029 TSecr=4253626233 4 0.033580346 192.168.1.13 95.142.156.18 TLSv1.2 364 Client Hello 5 0.055654137 95.142.156.18 192.168.1.13 TCP 66 465 → 12424 [ACK] Seq=1 Ack=299 Win=45056 Len=0 TSval=4253626267 TSecr=2845252041 6 0.064630882 95.142.156.18 192.168.1.13 TLSv1.2 1506 Server Hello 7 0.065507499 95.142.156.18 192.168.1.13 TCP 1506 465 → 12424 [PSH, ACK] Seq=1441 Ack=299 Win=45056 Len=1440 TSval=4253626276 TSecr=2845252041 [TCP segment of a reassembled PDU] 8 0.065515730 192.168.1.13 95.142.156.18 TCP 66 12424 → 465 [ACK] Seq=299 Ack=2881 Win=65344 Len=0 TSval=2845252073 TSecr=4253626276 9 0.065646720 95.142.156.18 192.168.1.13 TLSv1.2 823 Certificate, Server Key Exchange, Server Hello Done 10 0.066717836 192.168.1.13 95.142.156.18 TLSv1.2 192 Client Key Exchange, Change Cipher Spec, Encrypted Handshake Message 11 0.088334588 95.142.156.18 192.168.1.13 TCP 66 465 → 12424 [ACK] Seq=3638 Ack=425 Win=45056 Len=0 TSval=4253626299 TSecr=2845252074 12 0.088559696 95.142.156.18 192.168.1.13 TLSv1.2 117 Change Cipher Spec, Encrypted Handshake Message 13 0.188244024 192.168.1.13 95.142.156.18 TCP 66 12424 → 465 [ACK] Seq=425 Ack=3689 Win=66752 Len=0 TSval=2845252196 TSecr=4253626300 14 0.209855921 95.142.156.18 192.168.1.13 TLSv1.2 132 Application Data ... and continued with more traffic until completion. Just in case I'd got lucky with the random way that retries appear to work I tried the same process again. This time the first 'exim -Rf' failed to release the email but a second attempt worked. So it looks as if, for me at least, exim 4.94 has a high probability of failing to set up a SSL connection, especially on it's first attempt. The wireshark output for the successful connection shows the same pattern as I see with 4.93 which always connects successfully at the first attempt. > It seems like your successful attempt are at > 95.142.156.18(mail.gridhost.co.uk), but fails at > 95.142.156.8(mail-beta.gridhost.co.uk), > 95.142.156.16(mail1-a.eqx.gridhost.co.uk) and > 95.142.156.28(mail4-e.eqx.gridhost.co.uk). > > Could it be that you're finding a corner case in exim, because of that > circular dns resolving? mail.gridhost.co.uk does have multiple A > records, one of those has a PTR back to mail.gridhost.co.uk, where the > rest does not. I don't think there's any significance of the successful connection being made with 95.142.156.18, probably just the luck of the draw that it was that one that came up first that time. There were just as many failures with that address as with the other three over repeated retries in the test in my earlier post in this thread. Anyway my latest tests restricted exim to use only 95.142.156.18. > What SSL library is your exim compiled with? I installed exim from packages and can't see any obvious reference to which SSL library it uses but I assume it will be the standard version in base. -- Mike Clarke
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