I have looked thru most of the email apps, at least the free ones. And what bothers me is the ability to stop spams. Yes, many have ways to block spam from a sender. But this is of no use today were the professional spam senders constantly changes their address. What we need is a way to set up rules to block by certain phrases in the heading or the content. If I never want to see spams advertizing for bitcoin invertmensts, I could simply make a filter with "bitcoin".
Yes, I know.. Gmail has all these features actually! But if I for some reasons dont want to use Gmail I cant find another option. Also Thunderbird for windows does this exellent by the way.
The same goes for SMS apps. They all have the ability to block a sender by the number, but spamsenders never show their numbers. So it’s useless.