Mail is not sent or received on Plesk Windows server: queue overflowed

Symptoms

• Mail is not sent from the server.

• Cannot receive mail.

• No errors in MailEnable logs.

Cause

Too big (more than 20 000) outgoing queue in %plesk_dir%Mail Servers\Mail Enable\Queues\SMTP\Outgoing and/or %plesk_dir%Mail Servers\Mail Enable\Queues\SF\Outgoing

Resolution

As a workaround, rename the outgoing queue folder:

1. Connect to the server via RDP.
2. Rename directory %plesk_dir%Mail Servers\Mail Enable\Queues\SMTP\Outgoing and/or %plesk_dir%Mail Servers\Mail Enable\Queues\SF\Outgoing.
3. Create a new directory %plesk_dir%Mail Servers\Mail Enable\Queues\SMTP\Outgoing and/or %plesk_dir%Mail Servers\Mail Enable\Queues\SF\Outgoing.
4. Create subdirectory "Messages" in %plesk_dir%Mail Servers\Mail Enable\Queues\SMTP\Outgoing and/or %plesk_dir%Mail Servers\Mail Enable\Queues\SF\Outgoing.
5. To send the deferred messages, move them from the renamed directory to the new one in bunches by 1000 files and wait for them to be sent (disappeared from the directory).