To disable SpamAssassin for a given mailbox, when it is enabled globally, please follow these steps:
Enter your hosting Control Panel's Mail Manager section.
Follow the Filters link next to the mailbox you wish to modify.
Click on the Disable for this mailbox button to disable SpamAssassin for your mailbox.
Note: Generally, we would recommend that you keep SpamAssassin enabled as it protects your mailboxes from unsolicited messages.