DEFER Reason: 452 too many recipients received this hour

Question

_{Friday, October 16, 2015 8:06 PM}

Trying to troubleshoot a recipient stating that email from our domain is being received hours later.

Our Senders are in Office 365, sending to an external recipient.

When searching for the messages in the O365 Message Trace I find there's a "DEFER   Reason: 452 too many recipients received this hour" message...

What does this mean and how can we resolve this?

Thanks.

DEFER   Reason: 452 too many recipients received this hour
OutboundProxyTargetIP: [Removed IP]
OutboundProxyTargetHostName: mail4.domain.com

All replies (1)

_{Monday, October 19, 2015 7:39 AM ✅Answered}

Hi,

When you send too many e-mails, a destination mail server does not black list you, but instead it temporarily blocks access from your mail server (essentially the IP address of your mail server). You can contact the admins of the domain and request your IP address to be whitelisted.

it could also be that the message has been deferred due to insufficient system storage. Not your fault, they'll probably accept the mail later on once there's more space - it seems like your scenario.

Regards,

Melon Chen
TechNet Community Support

Please mark the reply as an answer if you find it is helpful.

If you have feedback for TechNet Support, contact [email protected].