E-post adress

How do I do to get the email address to one of this forums user in
order to send a file.

DevForums does not let you get an email address for an arbitrary user (for obvious privacy reasons). Nor does it support direct messaging (1). The easiest solution here is post your email address and ask the other user to get in touch; I encourage you to use a throwaway address to preserve your privacy.

Share and Enjoy
—
Quinn “The Eskimo!” @ Developer Technical Support @ Apple
let myEmail = "eskimo" + "1" + "@" + "apple.com"

(1) Even though it’s a much-requested feature, a fresh enhancement request against DevForums explaining your use case would be helpful.

If you want to contact someone, first make sure to post your precise question on the forum.

If you have no temporary address as eskimo advised, post your address and remove it by editing the post rapidly. After 1 hour, you will not be able to edit or remove the post and your address would remain permanently visible.