I'm having a problem sending an email to firstname.lastname@example.org and receiving this error.
Technical details of permanent failure:
Google tried to deliver your message, but it was rejected by the recipient domain. We recommend contacting the other email provider for further information about the cause of this error. The error that the other server returned was: 550 550 Administrative prohibition (state 14).
After checking MX record:
I noticed that "Reverse DNS does not match SMTP Banner" error.
I'm trying to figure out if there is an issue on their end and whether it is even possible to send emails or whether it has to do with settings on my end or my ISP. I'm trying to send it from gmail.