After Buypass introduced MPIC to enhance the security passing out certificate through ACME, we got problems when trying to obtain certificates. 

We are whitelisting their IP-subnett (185.62.160.0/22), with only this whitelist rule we could run certbot and get us a certificate for a webapp or a website. After they enhanced the security, ref: https://community.buypass.com/t/35ykp87/introduction-of-mpic-for-enhanced-security, we saw one of their IP's being accepted in our firewall. BUT we could also see several IP's from Azure. 

I reached out and they updated me regarding the choices they made for enhancing the security, but now there is NOT one subnet I need to whitelist, but several subnets and from other countries as well. Opening up for one subnet which is owned by Buypass is ok, but now the world needs access. 

I'm reaching out to the community to ask, how have you solved this? Do we know which subnets are sued, which FQDN's, or do Azure have an xml/json list over all IP's used for this product?