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I have a Pi3B running an older version of Raspbian. Not going to upgrade because there's a lot of stuff I and others have written to take advantage of this particular OS version. It's in the cards at some point, but not now.

I'm using the cron MAILTO= variable to catch and send any errors that jobs generate to myself. However, the cron daemon is adding the user's name to the FROM: address. For example:

user@ address@ mydomain.com

Of course, the mail host is rejecting this primarily because it knows that's not a valid user for the mail relay. (It never gets to the "this is a bad address format" check.) This seems to be the only system service that's doing this. Of course, everything on this one is running System======D.

WTF is going on here? I've disabled cron's MAILTO parameter and just have jobs writing to a log, but I'd like to figure out why it's doing this.

I have a Pi3B running an older version of Raspbian. Not going to upgrade because there's a lot of stuff I and others have written to take advantage of this particular OS version. It's in the cards at some point, but not now. I'm using the cron MAILTO= variable to catch and send any errors that jobs generate to myself. However, the cron daemon is adding the user's name to the FROM: address. For example: user@ address@ mydomain.com Of course, the mail host is rejecting this primarily because it knows that's not a valid user for the mail relay. (It never gets to the "this is a bad address format" check.) This seems to be the only system service that's doing this. Of course, everything on this one is running System======D. WTF is going on here? I've disabled cron's MAILTO parameter and just have jobs writing to a log, but I'd like to figure out why it's doing this.
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[–] • 1 pt

I’ve never run into that problem, but I usually redirect cron mail by setting a mail alias for the user running the job. That might be why.

I think cron’s MAILTO setting is only meant for usernames. In Ubuntu 24.04 man 5 cron says this:

If MAILTO is defined (and non-empty), mail is sent to the user so named.

The example there only sets it to a username, not a full email address.

None of that explains why it’s adding the username to the outgoing address though. It should be prepending it to whatever Postfix has myhostname set to.

[–] • 0 pt

I did notice that it never really calls out the ability to send mail outside of the local spool, but mailto should work with a fully-qualified email address (and does on every other system I run and have run.)

I have to assume there's some sort of bug in this version of cron when combined with a postfix relay running on the same machine. For now, I just have mailto set to "", and all of the jobs redirected to a file on the network where I just need to remember to look at it once in a while.

I may just remove the mailto variable altogether and see if it dumps mail into the local user spool.

[–] • 1 pt

I may just remove the mailto variable altogether and see if it dumps mail into the local user spool.

That’s what I would try right away. If it makes it there try setting an alias for that user.

[–] • 0 pt

As long as I can get the information somehow, I should be good.

It has the added benefit of removing all the errors from the mail.log...

Will make some changes later and see what happens.