I don't remember well how email works and I'm not in contact with
   riseup, but often a provider will send a bounce message back.
   Like [1]cock.li, the riseup folks try to do the right thing.  But their
   warrant canary system did reveal that the FBI forced their hand around
   2016.
   I haven't received emails from you =/  email is kind of silly in its
   insecurity, anyway.
   It's confusing to be a software developer who does not develop
   software.  The email problems should be easy to solve for ones who do.

References

   1. http://cock.li/