How to quickly check if an email has been sent to the right address

It often happens to me, a customer calls and is worried the email they sent to their supplier or solictor or whatever hasn't been sent.

Our usual response is to tell them to wait a couple of hours and call us if it still a problem.

Doesn't sound like a very logical troubleshooting approach I think you'll agree.

Well there is a better way. If you take a look at a web site called http://www.dnsstuff.com and scroll to the bottom of the page there is link in the centre of the page which will allow you to run a mail test. Simply plug in the email address that the customer spells out for you and away you go, not only will this tell you whether the mail servers for the detination are up and working but it will give you a fairly good indication if the receipient is spelled correctly (Not always I admit) however armed with this information and if you also get the customer to send an email to an auto-responder for example echo@esat.net which will normally bounce back a response in less than 5 minutes you can give your customer a much less vague answer and pretty much prove their email is working and possibly also spot if they got the destination email wrong.

Any other ideas out there how the above tip might be further improved ?