Opening mailbox page in Plesk interface on Plesk for Linux server fails: No such file or directory

Symptoms

Opening mailbox page in the Plesk interface Domains > example.com > Mail > Mail Accounts > john.doe@example.com results in the error:

Server Error
500 PleskUtilException 
mailmng-mailname failed: Unable to open dir /var/qmail/mailnames/example.com/john.doe/@attachments: No such file or directory System error 2: No such file or directory

Cause

Custom cronjob configured in Tools & Settings Scheduled Tasks (Cron Jobs) is set to remove empty folders in /var/qmail/mailnames with a command similar to:

CONFIG_TEXT: /usr/bin/find /var/qmail/mailnames -type d -empty -delete

Therefore, the @attachments folder that it was empty, was removed.

Resolution

1. Log into Plesk
2. Go to Tools & Settings > Scheduled Tasks (Cron Jobs) and remove the custom cronjob.
3. Connect to the server via SSH.

4. Repair the affected mailbox by executing the below command:

   # plesk repair mail john.doe@example.com