grammar - Thank you for X: ～をありがとうございます

I've often heard this pattern, particularly in things like

メッセージ／メール　を　ありがとうございます。

Since ありがとうございます is an adjective, why is it acceptable to use を in this situation? That seems about as grammatically correct as saying something like 雪を寒いです.

Is there some kind of underlying grammatical-correctness to this, or is this just something that was misused and then became acceptable over time?

Answer

I think your example is simply omitting a word (a proper verb after を, that is).

メッセージ／メール　を　（くれて）　ありがとうございます。

Which would mean this is basically like saying:

メッセージ／メール　を　くれて　うれしいです。

...ありがとうございます being essentially equivalent to ありがとうです. Of course, normally you don't say メッセージ／メール　を　うれしいです。, omitting the verb, but I think ありがとう is just so common that it might have become an exception.