There are a lot of people that have a problem verifying mail clients and there are lots of solutions that may or may not work.
I've seen that I have this problem every time my mail client (Catalina) tries to access a Hotmail account from a physical location that it is not used to. I get an email notifying me about a suspicious activity, which I mark as safe, but the mail still cannot verify the account (password is certainly correct). The only solution until now was to completely remove and add the account, but I cannot do this every single time I travel. It is getting ridiculous.
I understand that this is a security feature for my own benefit, but most of the time lately I don't have access to the mails. Is there any way to disable this feature? Or some other workaround?