Unable to move messages between folders while the IMAP connection: Permission denied (euid=30(popuser) egid=30(popuser)

Symptoms

• It is not possible to move messages between mail folders using any mail clients when the IMAP connection is established to the mailbox hosted in Plesk.

• The following error can be found in the /var/log/maillog file:

  CONFIG_TEXT: dovecot: service=imap, user=johndoe@example.com, ip=[::1]. Error: Mailbox INBOX.Spam: file_dotlock_create(/var/qmail/mailnames/example.com/one/Maildir/.Spam/dovecot-uidlist) failed: Permission denied (euid=30(popuser) egid=30(popuser) missing +w perm: /var/qmail/mailnames/example.com/one/Maildir/.Spam, we're not in group 0(root), dir owned by 0:0 mode=0775)

  ---

  CONFIG_TEXT: dovecot: service=imap, user=johndoe@example.com, ip=[::1]. Error: stat(/var/qmail/mailnames/exampl
  e.com/one/Maildir/.Spam/tmp) failed: Permission denied (euid=30(popuser) egid=30(popuser) missing +x perm: /var/qmail/mailnames/example.com/one/Maildir/.Spam, dir owner missing perms)

• The domain backup with the selected Mail configuration and content option in Domains > example.com > Backup Manager > Backup, fails with the error:

  CONFIG_TEXT: WARNING: (Mail object 'example.com') Not all the data from /var/qmail/mailnames/example.com was backed up successfully:
  /Maildir/one/cur: Cannot open: Permission denied

Cause

Incorrect permissions for the mail folders in /var/qmail/mailnames/ directory.

Resolution

1. Log into the server via SSH.

2. Run the command below to set correct permissions for the mail folders in /var/qmail/mailnames/ directory:

   # find /var/qmail/mailnames/* ! -user popuser | grep -v .spamtrain | xargs chown popuser:popuser