There's no such plugin.

There're only custom and paid solutions.

Well, now I've already replied to your email - not knowing you use WAMP - so I won't reply everything I wrote in the mail. Maybe just one thing: Crontrigger plugin has nothing to do with sending of validation email or other email messages sent by the Messages plugin because these emails are sent instantly.

Maybe the first step would be to get sending of emails working in WAMP and be sure that it really works. See https://stackoverflow.com/questions/5773288/configure-wamp-server-to-send-email for some advice that might help.

If for any reason the sending of mails doesn't work with the PHP mail() function outside of Elgg on your server, the only other way is using SMTP and setting up your Elgg installation accordingly. But that's what @Nikolai Shcherbin already posted links with advice for.

That link has a lot of good sounding information.  Looks like my dance card is full for the rest of the day. 

I wanted to update everyone who have been helping me with this external email problem.  The solution that iionly posted, the, "https:// stackoverflow.com/questions/5773288/configure-wamp-server-to-send-email" was the answer.  The external email dragon has been slain so now I can sleep at night knowing that this problem is solved.