Lately, I received emails from a customer something like 12 hours later...
So I checked closer and could see that the email was from hotmail.com.
On the server, I edited my whitelist to see what was going on:
Searching the list I could see hotmail.com, so why is it that it gets bounced with a 450 by Postgrey if it is whitelisted?
Looking closer at the logs left behind by Postgrey, I found this line:
Apr 23 06:33:34 m2osw postgrey: action=greylist,