I'd never heard of it before, so did a Google search for them, and discovered that they were a brand-new denomination or sect (they broke away from the Roman Catholic Church) founded last April, and that their main activity seems to be denouncing everyone they don't like, which seems to be, well, everyone (except themselves, of course).
I came across someone else who had received their spam, who seemed to assume, erroneously, that this particular sect somehow represented Orthodoxy: Not Healing the East-West Schism | Sinaiticus:
Like many pastors and churches in the Presbyterian Church (USA), I recently received (7/15/2011) an e-mail from the Byzantine Catholic Patriarchate, condemning our denomination’s loosening sexual ethics for church leaders. It is apparent that they culled the Internet for e-mail addresses related to Presbyterian congregations and sent out a massive spam.
The author of that blog is concerned about their role in healing the East-West schism. I feel I can safely say that they are as relevant to healing the East-West schism as the Westboro Baptist Church, which they seem to most closely resemble.
I'm not sure what the "Byzantine Catholic Patriarchate" stands for, but it reminds me of the Pogo comics of 50 years ago, when Pogo was accosted by the founders of the newly formed Jack Acid Society, who were going around recruiting members, and also, more important, denouncing enemies.
Pogo asked, "What does the Jack Acid Society stand for?"
"We won't stand for much, believe me."