Understanding sendmail, LDA , mailboxes
I had a problem where an application server that periodically checks a pop3 mailbox could not read a message (different format than expected).
Consequently the mailbox filled up. I tried to delete the 1st message in the mailbox, but when quiting the "mail" command, the os threw a segment fault. I decided I would save off the mail file and create a new one and deal with the backed up messages later.
I stopped sendmail with "sendmail stop".
[This is a redhat 7.3 machine, and 8.11 sendmail.]
Then I waited for all the sendmail daemons to disappear from the process list.
Then I did a cp and rm to the mail file.
However, even with sendmail stopped, the mailbox continued to fill up with mail.
I am trying to figure out what process continued to fill the mailbox, even with sendmail completely stopped.
Is it the LDA...procmail?
Is there something that empties the mail queue that is not sendmail?
I have also read that the files in /var/mail are hard links to /var/spool/mail. Was it just rebuilding the file from /var/spool/mail?
Right now there are also what look like "temp" files in both /var/spool/mail and /var/mail left over from the time when the problem occurred. They look like "_ZZH*.MYSERVER.MYDOMAIN.COM". What are these files? Can they be recovered?