What is the best way to retrieve the email from the following text:

Mr. Joseph Smith Jr. III jsmithjr@xxxxxxxx "J Jr."
-or it might be-
Joe jsmithjr@xxxxxxxx

So far, I have been able to use the substring-before and
substring-after in conjunction with the "@" to get a little closer to
the email, but not sure how to get the space which occurs before the @
and after the email (or end of string).