There's a free webservice you might use, I'm guessing it only
checks formatting:
http://www.webservicex.net/ValidateEmail.asmx?WSDL
If you open web services in Dreamweaver and give it the above
url, it generates
the cfinvoke code below, which you can drag into your code.
<cfinvoke
webservice="
http://www.webservicex.net/ValidateEmail.asmx?WSDL"
method="isValidEmail"
returnvariable="isValidEmailRet">
<cfinvokeargument name="email" value="mymy@dom.com"/>
</cfinvoke>
<!--- add code below to give Boolean, 'yes', only. If
email is malformed it gives an error. Use with a form and code to
check for 'yes'--->
<cfoutput>
#variables.isValidEmailRet#
</cfoutput>
If the email passes the above test, usual way is to send an
email to that address to verify the user exists, ask if they sent
the email, click return link to do something eg add them to
database, etc
Colm