I found this[0] a while back, because I always felt "thanks in advance" is just off somehow. They list the following alternatives as examples:

"I really appreciate any help you can provide."

"I will be grateful if you can send me this information."

"Many thanks for considering my request."

"I hope what I have requested is possible."

"In the meantime, thank you so much for your attention and participation."

Often I don't use these word-for-word. The point is, I think, to formulate a closer that's at least a bit customized for the occasion. Then the whole thing will just seem more natural, friendly and human.

I wish you the best email closers, npteljes

[0] https://macademic.org/2011/06/08/never-end-your-email-with-t...

I think it's ok to notify an email thread and say something like "Based on our last discussion regarding ____ , Bob is going to _____ . Thanks in advance for setting that up for us @Bob"

But yeah, thanks in advance can be a very passive aggressive thing.

A more flexible alternative would probably be "appreciate your expertise in setting this up for us"