I am using google app domain. Problem is that all mails are not delivering. If I send 10 mails, two or three are not delivering. Checked at firewall end. If any mail is coming to firewall, that get delivered. No issue with firewall side. error message is
The response was:
The recipient server did not accept our requests to connect. Learn more at https://support.google.com/mail/answer/7720
on: connect error (0): error]
There was a temporary problem delivering your message to firstname.lastname@example.org. Gmail will retry for 22 more hours. You'll be notified if the delivery fails permanently.
Last-Attempt-Date: Mon, 11 Dec 2017 17:16:30 -0800 (PST)
Will-Retry-Until: Tue, 12 Dec 2017 15:42:11 -0800 (PST)
Mails from all other domain are delivering. Only with one domain(google domain) has this problem.
The domain mx are
We checked all end and guessing problem is google side.
Thanks for considering my request.