Thanks Esmi
I agree. I don't Cf7 is a fault as it sends fine to other email accounts.
I'm struggling to find out why the email is not arriving at that one account.
Google Apps say that the email is 'not even hitting their server'. My web server IP is not on a Blacklist.
Are you suggesting my SMTP server may be refusing to send email to that particular Google address but will send to others? That would explain the situation.
Thanks again
Pete