Is it possible to capture emails address on aff link iframe and save it on my server ?

I think yes! And im trying to find out how. If any one knows pls give some help

This is something of interest if anyone knows how

You will need to use 2 steps.
Copy the exact look of the iframe.

First display ur mockup, when they enter email and click submit capture the email and redirect to the iframe one and display something like "Please try again" above the iframe.

Just be creative, this would be the only way since you cant access the contents of a remote iframe.