If you use MySQL as the whitelist, cleaning of the whitelist (expires after MaxWhitelistDays) does not fully work.
Assp will stop cleaning records after one key was found with prfrozen=1.
I had 885.456 records in my whitelist, but I saw that only the first 66.648 where updated.
Records 66.649 until 885.456 where mostly records which where expired (as old as starting 2011).
Then I noticed thet record 66.649 had a value for pfrozen of 1.
Changed it to 0 and the pvalue to the very far future (2050) and everything is OK now.
There is certainly need for whitelist-adresses that do not expire, we had pfrozen=1 for email-adresses which sends renewals of foreign domain-registrars.
They only send an email once a year, but it's very important that they go through.