Soldato
I suppose we'll see what happens.
There is no fighting his arrival in the company, so I have done what I can to make it as smooth as possible for me in the short term. If he wants to use his knowledge against me, today's e-mail would not have made any difference.
the difference it makes is that he now knows there is some level of fear that he can exploit. It may sound insignificant, but it's planted that small seed in his brain that he now knows your are already half way bent over a barrel.
Imagine a promotion opportunity comes up in 6 months time. You both want to go for it, he casually slips in the fact that he thinks he is more suited and that you should consider not going for it because he has "dirt" on you. His read on you now is that he can take you to the cleaners.
People are weird folk when it comes to self preservation and taking care of themselves first.
That's why the not playing your hand at all and keeping quiet in these situations is the best. First rule of business is never trust your colleagues for they will not bat an eyelid while they carve you up to get themselves ahead of the game. When it comes to getting a better paycheck there is not such thing as friends or trusted colleagues at work.