I am trying to set up
nullmailer to use
smtp.mail.yahoo.com as relay host for my home desktop computer (Debian buster). My attempts so far have failed, and I want to debug the problem.
So far I have relatively limited information of what is happening. In particular, it is not clear to me what is it, exactly, that
nullmailer is sending out (to
smtp.mail.yahoo.com?), and what is it, exactly, that it is receiving (from
My question is: how can I log, verbatim, all the communication, both outgoing and incoming, that happens between my MTA and the outside world?
My immediate interest at the moment is to do this troubleshooting for the scenario
- relay host:
...but I am interested in general solutions to this problem, since it is likely that my troubleshooting will require comparing the communication that currently takes with my home machine with what happens with a more successful set-up (most likely (1) an MTA different from
nullmailer, but still using
smtp.mail.yahoo.com as relay host; or (2)
nullmailer using some non-Yahoo external server, such as
smtp.gmail.com, as relay host).