pgaskin wrote: Yes but how do we prevent this. Is there a way to check the email address for mistakes?

Not without physically sending the email.

pgaskin wrote: What do you mean? "Not without physically sending the email."

Is there a plugin to check the email address for typos/errors?

Proper email format is checked - you cann enter something like xxx@yyy as it is not a valid email address format.

But there is no way to check is email xxx@yyy.com has a typo (example extra x or extra y).