For those times when CFMail Just won’t cooperate, rather than throwing only an error message, give your user a chance to send the email from their own mail client on their PC/device. If CFMail fails the user is provided a link which opens Outlook or which ever Email client has been chosen on their PC.
<cfset mailerr = "Email Sent"><!---default message --->
<p>Dear Whoever,<br /><br />
<cfset mailerr = "There was a problem sending the email.">
Webmail System Error: Please click here to send a manual Email via your PC.</a>
Then output the mailerr