Rogue email being sent by PBXAct

I posted earlier that I was having difficulty getting my SMTP mail to work with Office365. There was a couple of you that offered fixes though I have yet to get it working. While I am working to get it working, I am using GMail.

My current issue is that I am getting emails sent to GMAIL from the system and I am not sure why. THe other issue is how to configure the MX record to allow the mail to get through. Attached is an excerpt from one of the emails.

Your assistance is appreciated.

Address not found
Your message wasn’t delivered to [email protected] because the domain couldn’t be found. Check for typos or unnecessary spaces and try again.

The response was:
DNS Error: 28717019 DNS type ‘mx’ lookup of responded with code NXDOMAIN Domain name not found:

you would need fix their DNS records

As I am and the person would would update the DNS records, what needs to be added or adjusted?

I would think that I need to make an additional MX entry, though I am thinking outloud and truly looking for advice.

Thank you,

you would create a sub-domain named uc-56518038 and have a mx record or two

But you probably are better off hsving your mta rewrite the subdomain.server with just server

If postfix, then a quick google spat out

I apologize that I didn’t speak clearly when posting my question - and frankly, didn’t read the email that was bounced well enough to understand.

I’m blaming old-age, though…

Thanks all.