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When is it correct to use the word "as" and "for" in the sentence below?

Sarah, please extend my appreciation to David Sicht, Kelly Ong, and David Yee (as/for I do not have their contact info) for all their help.
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You can use as, for, because, or no word at all, and you can put the parenthetical remark at the end. In terms of the sentence itself, here's how I would probably write it:

Sarah,
Please extend ... to ... for all their help. (I don't have their contact info.)

In terms of the situation, however, I would get the contact information from Sarah and thank them myself.

CJ
Comments  
I'd use "as" or "since". "for" is possible, but in this sentence it seems overly formal and literary (or even old-fashioned) to me.

I'd try not to break the main clause like this. You could say:

"Sarah, as I do not have their contact info, please extend my appreciation to David Sicht, Kelly Ong, and David Yee for all their help."