How To tell if an email on a cPanel server has been read from the command line

All of the emails in the email directories contain one of the following at the end of the filename

$ ls cur/ | cut -d: -f 2 | sort | uniq -c
54 2,               <- Not Read
12 2,ab             <- Not Read
83 2,S              <- Read
61 2,Sab            <- Read

The first two “2, and 2,ab” mean that the message has not been read. The bottom 2 “2,S and s,Sab” mean that the message has been read or “seen?”. Guess that is what the S is for. Not sure what ab is for.

imapsync – NO [OVERQUOTA] Not enough disk quota

msg INBOX/4624 {75129} couldn't append  (Subject:[Email message]) to folder INBOX: Error sending '55 APPEND INBOX (\Seen) "25-Aug-2017 09:12:05 -0600" {75129}': 55 NO [OVERQUOTA] Not enough disk quota (0.001 + 0.000 secs).

To resolve the above problem, check the following

  1. Email mailbox allocated size
  2. cPanel account user Quota

The above problem was due to the fact that the cPanel User Quota was maxed out. Increasing the space allocated to the account resolved the problem.