So this appears to be an age-old problem where folks report that system generated messages by cron’d shell scripts executed have output that would normally be sent to the screen are redirected to Root’s mailbox /var/spool/mail/root, also linked to /var/mail/root.
So, mine stopped around 0500hrs, based on my observation by reviewing messages delivered to my /var/spool/mail/root file.
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I reviewed the df output for /var/spool/mail, which resides on the partition /var; it was only at 2% full.
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I determined that the mailbox_size_limit default setting, using the command
postconf -d | egrep mailbox_size_limit
was = 51,200,000 bytes
(commas added here for readability) which is approximately 48.828125 MB. -
I determined that the file /var/spool/mail/root was only 164KB, an order of magnitude smaller than 48MB.
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I also determined the current limit is also set to the same values (which makes sense because I did not alter it).
I attempted to restart Postfix and the delivery of new mail messages did not start back up.
I observe this problem at work too.
So, what needs to be done to fix this? Why is it happening? A denial of service attack is not a concern for me at my home, but it is at work of course.