Blacklist Settings dialog
When AY Mail loads a blacklist, it doesn't dispose of it right away in case you resume sending within a short period of time.
You can choose for how long AY Mail keeps the blacklist loaded. Longer delays will let you avoid importing the blacklist over and over again, but impose a danger that the blacklist will be outdated by several hours.
Blacklist remains valid for You can use any delay between 0 and 48 hours.