how to confirm the email address

if you enter a personal email address (gmail, yahoo, outlook, etc), the email will get to them INSTANTLY.  There is not need to wait few minutes.  If it is not there in 15 seconds, there is a 99% probability that the email address is mistyped. 

So the ONLY WAY YOU KNOW if you typed the correct email address is to have the professional confirm their receipt of the email.

If you entered a business email address, they may never get the email conformation as their company may have email filters that delay or block emails

(the professionals do not know that their company blocks some emails as they do not know that they do not get some emails)