Re: [exim/exim] [Bug]: Exim 4.99.4: Possible duplicate Gmail deliveries caused by SMTP/TLS session completion issue (Issue #3229)

Assuming there are 2 logged receive ( "<=" ) items, Exim thinks it received the message (twice), as separate items.
It should have responded with a 250 SMTP response to say so. You could run Exim with debug enabled,
which would show the attempt to do so.

Next step deeper would require a packet capture - and given that TLS is in play, transferring the TLS session
key for each connection to wireshark. Exim supports the standard SSLKEYLOG environment variable for this;
you can add it in your exim config with a main-section option setting like:

add_environment = SSLKEYLOGFILE=mydir/sslkeys

* and you need to tell wireshark about that file: edit / preferences / protocols / tls / master-secret-log-filename
* and you need to run Exim with debug enabled.

If your tls library is GnuTLS this also requires explicitly running Exim as root (not relying on suid).
OpenSSL is more relaxed.

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View it on Exim Forgejo ( https://code.exim.org/exim/exim/issues/3229#issuecomment-239692 ) or reply to this email directly.