Hi sr508As far as i know Campaign cannot validate if a email address is
valid or not however there are few websites which i think can. Now in
order to check if an email has been sent or not to a particular
recipient, you can open the delivery and click on delivery tab and there
you can see if the email has been successful or not. If an invalid user
is targeted then then status for that user will be failed and reason
column will show the text. For example mailbox does not exist, invalid
user, et...