There is a logging option:
log_selector = +smtp_confirmation
From the docs:
> smtp_confirmation: The response to the final “.” in the SMTP dialogue
> for outgoing messages is added to delivery log lines in the form
> C=<text>. A number of MTAs (including Exim) return an identifying
> string in this response.
For exim the entry on the "=>" line looks a little like this:
C="250 OK id=1V2XUp-0005jj-9Z"
Gmail:
C="250 2.0.0 OK 1374826502 gg6si20604438wjb.120 - gsmtp"
This is a confirmation that the email has indeed been delivered to the
appropriate server. After that it is out of your hands what happens,
but this is proof that a particular message has been sent and accepted
(asuming it isn't backscattered back again).
You can quote this in the event of any dispute over whether the mail was
ever sent.
Note that the receiving server's Message ID is given to you which is
useful evidence of acceptance.
--
Regards,
Martin Nicholas.
E-mail: reply-2013@???
