His number is probably wrong. I personally wrote/typed my email address wrong (when you have those two fields).
There are also common pitfalls people are doing like empty spaces at the beginning and at the end which should be cleaned up before trying to send the email to " whoever@gmail.com".
There is also an Email standard and when a normal library is able to validate it (and there are free good libs out there) than the effort to do so is similiar minimal but provides an additional support.
What you should do is also to make sure that you are not sending unlimited emails out there. Otherwise you might be missused as a mail relay / spammer.
There are also common pitfalls people are doing like empty spaces at the beginning and at the end which should be cleaned up before trying to send the email to " whoever@gmail.com".
There is also an Email standard and when a normal library is able to validate it (and there are free good libs out there) than the effort to do so is similiar minimal but provides an additional support.
What you should do is also to make sure that you are not sending unlimited emails out there. Otherwise you might be missused as a mail relay / spammer.