Sendmail logs from root to root
Since a few days, my AWS Opswork PHP instances are logging tons of sendmail lines with "from:root" and "to:root".
Those fail, but I'm more concerned about why sendmail would send emails to the local root.
Here are a few insights:
- I inherited from the app, so I'm not sure how the setup was done
- from what I understand it's using SwiftMailer via Amazon SES to send emails, and AFAIK people do receive the emails as intended
- those are emails from root@localdomain to root@localdomain
In fact I answered myself in between.
Sendmail is acting on crontab's behalf.
I had php scripts run by crons. They are writing to the standard output, which is useless in cron mode. Crontab just send the standard output via email, and if no other email is set, it sends that to its user (local root, no comment on that).
Hard to say what changed on my server for it to show, but I know how to fix it : I'll run my cron in quiet mode.
Emails "from root to root" are widely used to report problems/error. You SHOULD+ redirect emails to root to non privileged account.
Sendmail by default sends copies of some delivery failures reports to postmaster. postmaster is by default aliased to root. What you report may indicate present alias for postmaster and missing alias/redirect for root.
Check/modify /etc/mail/aliases or /etc/aliases file. Run newaliases command after changing aliases file.