Many companies have already blocked the UCEPROTECT server globally as they are known for their shady tactics and false positives.

Here is an article from the well-known security company Sucuri, on this topic:

https://blog.sucuri.net/2021/02/uceprotect-when-rbls-go-bad.html

Here is another that talks about the extortion that this company was doing, as early as 2009:

http://www.securitybydefault.com/2009/12/el-negocio-de-las-listas-antispam.html

The Telefónica Group, which has tens of millions of IPs, is also listed.

For an antispam system to be reliable, it must follow fair standards agreed by the majority of trusted IPS's in all countries. These rules are summarized here:

https://www.abuses.es/docus/abuses/urln.html

If a mail server rejects your emails because your IP is on the UceProtect Spam lists, it is a mail server that does not follow the guidelines recommended globally by the main Internet mail providers, and therefore it is a totally their problem and not yours, and in which case, your server/IP are NOT responsible.