You have the same error, i.e., sender email rejected.
Make sure your credentials for privateemail.com are correct. For example, does it require an app-specific password? Moreover, the sender and authenticated user probably need to be the same for your service unless you create an alias for the alternative address.
Why you don’t use SMTP Mailgun instead, it just cost you 5 minutes to create account and free. BTW, Mailgun is used for ghost newsletter, you must have one for sure.
Maybe my contribution to this conversation is too obvious, but for me the solution was to correctly place the link I created in mailgun. As you can see in the image.
This service is essentially for receiving email, and isn’t a relay service.
Nonetheless, it’s not clear what diagnostic steps you’ve taken. Did you, for example, manage to send a test message via SWAKS? The error message suggests that the problem is with your email service, and it would be good to confirm this.
Moreover, simply changing port to 587 won’t work as you’ll need to adjust the config for TLS and insecure negotiation.
This is for newsletters, not transactional email.
Same here, and the ideal solution. The OP should do this, and use Private Email for receiving messages.