I am using Ubuntu 15.10 and I have an email account configured on the terminal.
Probably a left-over from the time I tried to configure that account, I have some logs being printed to a file in my home directory a couple of times day.
An example of a log (one line, split here for readability):
28 12:36:02 host=smtp.gmail.com tls=on auth=on
user=***@gmail.com from=***@gmail.com recipients=&&& smtpstatus=553
smtpmsg='553 5.1.2 The recipient address <&&&> is not a valid RFC-5321 address. q65sm28155223wmd.6 - gsmtp'
errormsg='recipient address &&& not accepted by the server' exitcode=EX_DATAERR
It is printed to ~/msmtp.log
My question is how can I discover where does this printing comes from in order to kill it?
Solution: The log was printed by msmtp itself. A quick look at the msmtp manfile showed that the configuration file is ~/.msmtprc . I edited this file to change the log file.