Looking on the internet deeply has found these results:

I will let you know is the most popular phrase on the web.

I will lets you know 110 results on the web	I will let you know 118,400,000 results on the web More popular!
Some examples and use cases from the internet:	Some examples and use cases from the internet:
Feb 2, 2011 ... ... called Mean While. it will be printed soon, so when that happens I will lets you know. Its gonna be full color so I really excited for the outcome. 2011년 11월 24일 ... I am a Korean and I will lets you know real history of Korea one of the great empire. I agree that Mongol is elder brother of Korea. However.... May 28, 2014 ... cool, am working on a endless runner game, as soon as i get the terrain and the characters ready, i will lets you know. send me what your pay ... Jul 4, 2009 ... Commented on 8.March 2011. I'll try this and after i will lets you know. Chetan. Commented on 9.March 2011. i want to write the PROPEQUITY ...	But I will let you know when you cracked the case. When I have achieved what I have set out to achieve, I will let you know where to find the guns. Not yet, but I will let you know. I will let you know if I meet anyone innocent. Duke, if I find out anything pertinent relating to your imminent demise, then I will let you know. I will let you know when it is finished. I will let you know when I have those results. But I will let you know what he says.

I will lets you know

110 results on the web

I will let you know

118,400,000 results on the web

More popular!

Feb 2, 2011 ... ... called Mean While. it will be printed soon, so when that happens I will lets you know. Its gonna be full color so I really excited for the outcome.
2011년 11월 24일 ... I am a Korean and I will lets you know real history of Korea one of the great empire. I agree that Mongol is elder brother of Korea. However....
May 28, 2014 ... cool, am working on a endless runner game, as soon as i get the terrain and the characters ready, i will lets you know. send me what your pay ...
Jul 4, 2009 ... Commented on 8.March 2011. I'll try this and after i will lets you know. Chetan. Commented on 9.March 2011. i want to write the PROPEQUITY ...

But I will let you know when you cracked the case.
When I have achieved what I have set out to achieve, I will let you know where to find the guns.
Not yet, but I will let you know.
I will let you know if I meet anyone innocent.
Duke, if I find out anything pertinent relating to your imminent demise, then I will let you know.
I will let you know when it is finished.
I will let you know when I have those results.
But I will let you know what he says.