@benjamineskola@hachyderm.io I really want to avoid limiting to much, because it breaks the flexibility. I could limit the connections or bandwidth, that could maybe solve some issues. On #BoxyBSD I had to limit the whole smtp traffic within the first two days and provided an smtp relay which had to be used and performed rate limiting on outgoing mails. I think my biggest fear is to deal with illegal content provided on these systems. Currently, I fully rely on my self-awareness of people how they react on social medias, I do not even have their names, of some I even don't know where they're from. And the xz debacle shows how quickly trust can be abused...

Currently I only see:
* Providing dummy fee by CC, SEPA or PayPal (or a small onetime setup fee). But dealing with money means to have much more data safety in place. I do not want to have knowledge or any thing else of banking data etc. Next, it could lead into issues with tax offices.
* No joke: Sending a real letter to the residence address of a user (which just takes too long, overhead and money from my site to send a letter)

I already use dedicated networks for this service to be at least safe from blacklist etc. for my personal systems. It's really a pity...