SymptomsIf you have more than 100 email addresses added into SA White/Black List and are trying to add more, the message like below appears:
Only -12 First Unique E-mail Addresses Will be Added
CauseSpamAssassin black/white list feature may cause too high server load if there are many addresses are listed in black/white lists. So that this value in Plesk 8.1 was limited to 100. The message shows how many addresses can be added and this value is equal 100 minus total number of messages in the list and can be negative if more than 100 addresses already entered.
ResolutionThe ability to configure maximum number of messages in the Spamassassin white/black lists should be added in Plesk 8.4 version.
Refer to the following article for details: Increase maximum number of addesses that can be added to the Spamassassin White or Black list.