@nielsa I have a small mail server on the same ipv4 address for the last two decades. I have looked for alternate European vps, but most do not allow normal mail traffic dute to UCE. An understandable situation. I would hope for electronic independence a European VPS might allow email with suitable attribution and documentation about the owner and them being responsible.
So my ask would be the provider maintain a respectable address block, and have channels of communication to the big providers. Linode has done a great job at this, even for small accounts.