Hi Leonid S 

You may place it to the "Terms of use" and add the option that the user agreed with that as mandatroy checkbox.

that is one way yes, but I still think that popup or function in register form where email is entered would check against a list as mentioned above and it would turn red as "this email domain is prohibited"

Why am I doing such a fuss about this you my ask..., well it is very annoying getting all this mail bounced back as undelivered since mail box does not exist. Since I run my own e-mail server I need to worry about reputation as well.

So, can you consider something like that as future enhancement as security / anti spam prevention?

Or can someone please help me out with how to implement this list:
https://raw.githubusercontent.com/martenson/disposable-email-domains/master/disposable_email_blocklist.conf 

 to be checked upon registration and to prohibit the use of such mail address

Kind regards
Mayki

Yes my dear LeonidS , and I do wish I'd know how to code it.

But I don't . Unfortunately.