I recently started using the iCloud+ Custom Domain. While the email is fully connected to my GoDaddy domain, my website, handled through WordPress, sends the emails, but these are not arriving at the recipient.

This may be due to the SMTP configurations. I bought WPMailSMTP to handle the SMTP validation with iCloud+ so that my emails are received.

After following the iCloud Mail server settings, as described here by Apple, it is not working.

I have tried everything (as far as I can tell):

Using TLS instead of SSL
Using a different port number
Using my Custom Domain Email & App-Specific Password
Using my @icloud email with my password and App-Specific Password
Using the email I use to login into Apple with my password and App-Specific Password

I would like to use my iCloud+ Custom Domain to send notification emails from my Website (when people complete Forms) & to use it for communications regarding my website. Also for user login welcome emails and reset password emails.

Any help would be highly appreciated.