I think they're using SpamAssassin so don't expect world leading spam filtering. But, they allow you to write your own sieve scripts so you can really customiz

I think they're using SpamAssassin so don't expect world leading spam filtering. But, they allow you to write your own sieve scripts so you can really customize the experience a lot. Don't think of them as another proton mail, they're much more a DIY mail provider.