We have ran Network Edition 4.5.6 for over a year and recently we finally upgraded to 4.5.11 (yes - baby steps, we did not yet go to 5.x).

However, ever since the upgrade to 4.5.11 every 1-3 days the POP3 stops responding. Basically all of our customers using POP3 stop receiving email.

Through tests during these times I can tell you that IMAP still works, SMTP still works (everyone can send emails). However, just our customer using POP3 stop receiving emails.

The fix, so far, is to perform a zmcontrol stop/start which corrects the problem for a few days.

Does anyone have any ideas, where I should look for possible problems, etc.

Thank you for any assistance or information,