I haven't used this myself, but I have heard the phrase "Don't forget who brung ya" when someone is promoted to a new position. I don't even know where that comes from (and I should, since I love the origins of words etc), but it makes me picture a young couple that went to a dance and they are not necessarily engaged for long term, and then one of them meets a star. The one who "brung" the other to the dance says "you have to be happy, but don't forget me, at least I brought you here."
Was that all just out of my imagination? It didn't really happen to me, but I hope I would be just as noble.
I don't think there is a reason to inject something identical to that analogy into an email for public consumption. But I think the feeling exists. In my announcement I would introduce the person in their new responsibilities that are going to rest with that person (and that you're happy to tell everyone about); and also include some background on a list of good things the person worked on, and the good departments that person worked with or in. Good things come from good places and other places, and sometimes good things come from the same place in a promotion context.) Write from the mindset that this is something everyone should be happy about. | 
