I'll take that downvote - that's what I get for posting before coffee first thing in the morning. :-)

BUT - "sendmail -bv" still sends mail. A DSN is sent back to the user who ran the command - and that address is even less clear! Probably just $USER from whatever environment spawned sendmail, but the manpage doesn't seem to say.

Also, in generating the DSN, sendmail follows its delivery rules - so -bv to test@test.com is going to generate network traffic (SMTP dialog up to "RCPT TO" it looks like), possibly directly to test.com, depending on how the local sendmail is configured. Enough stuff like that in the logs never looks good.

So how about I leave it at this: any time you're writing a program to send email, be extra careful about what addresses the mail is To and From, because when things go wrong you may never notice.

And I get to learn something new about sendmail today. :-)