python – Email validation blocked by Spamhaus

I can succesfully validate newly generated email adress (check if mx record exist) if it’s a Gmail, but when checking Hotmail adress I get the following:

b’550 5.7.1 Service unavailable. Client host blocked using Spamhaus.

I am using a VPN IP so I understand that it has to do something with that, but Gmail-adresses is no problem for this.

What solutions do I have to be able to bypass a Spamfilter like this?
If I have to use a proxy, what kind of Proxy do I need for email validating?

I am validating with Python 3.8.3 in Ubuntu 20.04.