KryptoMail - first usable mobile emial client with encryption
In the past years I did several tries to get email encryption to work. On desktop it is okay with GPG Tools. But the usage on mobile and specially iOS was a mess.
Now KryptoMail appeared and it seems to be the first convinient iOS mail client including mail encryption.
There are still some features missing, like keyserver support, but as the fast responding support mentioned, they have a tight timeline for furtherf features to come.