Just started last week... 451 4.7.500 Server busy. Please try again later

Question

For the last week or so, I am intermittently recieving these "warning" bouncebacks from various outlook email recepients. Deferred: 451 4.7.500 Server busy after 4 hours of non delivery. Nothing has changed to my knowledge and at times the messages seem to go through fine. I can't operate my business this way and cannot find a way to actually speak to anyone that can resolve it. Last posts on this issues seem to be from October.

Answer 1

Hi @Jason Cheskes

This error code may often be seen if the ip address you are sending from is throttled due to sending a large number of emails within a period.

While kindly note that here in Microsoft Q&A forums we mainly focus on Outlook application issues.

If you are having trouble with sending to outlook.com recipients, please post in the Microsoft Community.

Thanks for your understanding.

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