That the server only sent e-mail but did not receive it isn't exculpatory by itself. Most receivers will do a reverse DNS query (PTR); some will even do queries

That the server only sent e-mail but did not receive it isn't exculpatory by itself. Most receivers will do a reverse DNS query (PTR); some will even do queries by walking the Received: header chain as part of anti-spam measures. And if the server was indeed sending e-mail (or similar activity) through a relay, that makes the peculiar Alfa and DeVos activity even more suspect.