Thanks for responding. Could you say who it is? Because unfortunately, a common response of corporate wrongdoers is to blame the problem on someone who has now definitely been taken care of.
And while I'm asking questions, jaquesm says, "the sender is mailscarp.com". Was it actually sent through your servers? It looks like mailscarp is only inbound, so I don't understand how one of your beta users could have spammed a bunch of people on your behalf.
Thanks. Then maydemir's explanation doesn't hold up for me. The Mailscarp page doesn't say anything about the features he describes. It seems like the simpler explanation is that they just tried spamming people and got caught. I hope that's not the case, and I hope they'll respond to questions to straighten things out.