Today I got an SMS that my mailserver was bouncing mail from someone. In first instance it was unclear to me why it was blocked, but after analyzing further I found out that by default the cloud outlook mailservice of microsoft is being blocked by many mailservers. Because the name of the server is using ‘pool’ in the domainname lookup:

greylisting filter[539]: list type: black, from: ch1outboundpool.messaging.microsoft.com, match string: dsl|pool|broadband|hsd

So missing important emails is a big failure and even a bigger bummer when you do not know exactly why. Ok I added the mail adres in the whitelist, but it would be better to allow such kind of domains sending mail.

So how to do this in plesk with greylisting?

See first with ./greylisting -i (info-Server) that it is indeed blocked

./grey_listing –update-server -domains-blacklist del:”dsl|pool|broadband|hsd”

this will remove it and with ./grey_listing -i you can see