during the last week, couple senders are received bounced back email when they tried to send email to our domain, their email first were delayed and they received an email like this:
Warning: could not send message for past 4 hours
Then after two days they received an returned email like:
Returned mail: could not connect to DNS 66.113.95.11
They can send email to anyone else but not us, and we received emails from others also but not from these couple companies.
What should I do to resolve this?
Thank you for any help