Prescient spam

I work in area X. I recently wrote a paper on area X_1, and submitted it to a conference. It was rejected. So I revised it and resubmitted it to a more topic-relevant conference, and it is currently under review. There is absolutely nothing in the public sphere indicating that I have done work in field X_1 that I am aware of.

Today I got a spammy email from one of those shady journals that spams anyone who ever published something in IEEE Xplore or the ACM Digital Library, saying:

Dear Dr. FCS,      // Not a bad start, calling me "Dr." instead of "Ms." (or "Mr.")

Our Journal of X has a special issue coming up on X_1. Given your expertise in this area we would like to invite you to submit something. 

Sincerely,

Editor in Chief of Shady Journal

Mostly I am fascinated that they somehow know I am working in area X_1. Looking at the editorial board of the shady journal and the PC of the two conferences this paper has been seen by, I see no obvious overlap.

The funny thing is, this journal never spams me on areas of X_2, X_3, or X_4 (none of which I work in, but they publish in), so this is fairly deliberate spam.

So how did they know about my new professional foray? Clearly this is evidence that they are psychic. Or one of my reviewers blabbed. I'd say it's a 50/50 probability of either.