This can happen after upgrading to SBG 9
If the dates shown in the alert are not recent, it means that there is some old data stuck in the mysql DB about a failure in replication. Deleting the historical data will make the notifications stop.
In order to check it, do the following:
access to control center as support user (Use the set-support command to set the password)
Run these commands:
cd /opt/Symantec/Brightmail/mysql/bin
mysql -h127.0.0.1 -ubrightmailuser -p`cat /data/etc/.brightmailuser` brightmail
select * from status_user_pref;
Delete the lines with failed status using the command:
delete from status_user_pref where id=x;
As you can see the timestamp of the failed replications are the same as in the alert email.