SMTP can't send to personal domain email address

A friend using eM Client on Win 8.1 can send email to my gmail account, but can not send to my personal domain email address which is then forwarded.

Using a web browser, both emails are shown as “sent” the gmail one gets delivered the personal domain one just disappears. No errors shown.

Using the web browser, he can send an email to my personal domain email address that then gets shown as “sent” and is delivered.

The same issue can be replicated in the Win 8.1 native email client. Also, the same occurs when he tries to send to the personal domain email address of my wife.

I am now really confused. Any help would be very much appreciated, or some guidance as to where you think I can investigate further. Many thanks.

Hi, can you please go to Tools > Settings > Advanced and turn on SMTP logging for the problematic account?
Save the settings and restart the application, then please try sending the email to the personal domain email address you’re having difficulties with and if the issue occurs go back to the advanced settings window and click on “Send Logs”, please add my email as a copy (mcgregor@emclient.com).

Also please add a reference to this forum topic (link will do) as well.

Thank you,
Paul.