Registrations have been blocked for common email domains where for example, Microsoft continued to block them. So there is no use in users trying to register with such email accounts anymore. I'm sure a lot of people are aware of my epic long battle with Microsoft and I have given up trying to get off their blacklist. So I no longer allow registrations using Microsoft related accounts.
However, it is just come to my attention that some people still have not switched away from such problem accounts on the forum. Unfortunately you are going to get continually blocked by CleanTalk and a lot of people are already not getting email notifications because Microsoft have been blocking them for years now. The amount of bounced emails I get because of these email accounts..!!
So if you have one of these accounts, you need to change your email address, or if unable, contact a Admin to change it for you. Otherwise you will not be able to post on the forum. Or any other accounts which Microsoft related or likely to have the same problem as well. Also note I'm also blocking t-online.de as they are blocking my server as well and I really cannot be bothered to battle with them as I have previously mentioned.
I was almost tempted to send out a mass email to all forum users as a test to see if they get emails or not. However when I have sent a mass email out before I generally get multiple people giving me abuse because they apparently have never signed up with the forum and want to be removed!

I have been thinking of setting up a email test page so people can verify if they are getting emails. In particular for store orders where receipts go to and often go missing. If people would find this useful then I can write a quick test page to do just that. People of course would have to be logged in for it to work.