- Plesk 12.5 for Windows
Note: This article has the reference to the issue with the fix available:
"Mail sent from domains in the Spam Assassin black list was delivered marked as spam even if the “Delete all spam messages” option was configured in mailbox settings."
- Plesk 12.5.30 Update 63 04 April 2017 (Windows)
SPAM emails from blacklisted mailboxes being delivered if Delete from server option is set for What to do with mail that fits the criteria parameter in Home > Tools & Settings > Server-Wide Mail Settings
This is software issue #PPPM-4518 that was fixed in Plesk Onyx.
Upgrade to the latest Plesk version .