I am just passing on, with permission, something exim related from the mai...@mailop.org list. https://list.mailop.org/private/mailop/2021-December/020647.html On 02/12/2021 12:50, Andrew Hearn via mailop wrote:
Hello, We're a UK ISP, and relay email for our customers as well as send our customers emails such as invoices. We currently have about 1,000 emails queued for google accounts and these are failing with a timeout, eg from exim: 2021-12-02 11:48:05 1msize-005feQ-DI H=gmail-smtp-in.l.google.com [142.250.13.26] TLS error on connection (send): The TLS connection was non-properly terminated. 2021-12-02 11:48:05 1msize-005feQ-DI H=gmail-smtp-in.l.google.com [142.250.13.26]: SMTP timeout after sending data block (525043 bytes written): Connection timed out Based on past experience, eventually, the emails may will through. This is also intermittent, as sending to my own gmail address tends to get through eventually, though they do still time out once or twice before eventually getting through. Generally these emails do show as SPF/DKIM/DMARC PASS in gmail. This report is rather vague, but we do have further examples, logs, pcaps. Is someone from google on this list able to help investigate this problem with us please? I can pass examples and pcaps privately. Thanks! Andrew, AS20712 aa.net.uk
In https://list.mailop.org/private/mailop/2021-December/020659.html he followed up:
After trying a few things, disabling TCP Fast Open seems to have worked... My mail queue is being delivered successfully to Google MXs! A bit more about our system: Stock Exim from Debian 11, using GnuTLS. Exim version 4.94.2 #2 built 13-Jul-2021 16:04:57 And I added: hosts_try_fastopen = to the outbound smtp transport. Andrew.
-- ## List details at https://lists.exim.org/mailman/listinfo/exim-users ## Exim details at http://www.exim.org/ ## Please use the Wiki with this list - http://wiki.exim.org/
