[mathrawka]

So he deleted his email address or sigaint removed it:

Requested action not taken: mailbox unavailable 550 Invalid recipient

[mike-cardwell]

Unsurprising. On their signup page at http://www.sigaintevyh2rzvw.onion/ it says:

  Are there any rules to using this thing? Generally we are 
  pretty chill, all we ask is that you don't use our FREE 
  service to:

  Spam people
  Threaten people
  Harm people

  Everything else is cool with us.

Looks like he broke rules 2 and 3.