Exchange error: [0x80004005-0x80004005-0x000501]

When users were sending emails to a contact group, it would bounce immediately with the following error message:

From: System Administrator
Sent: Monday, August 14, 2017 3:14 PM
Subject: Undeliverable: Email subject

Your message did not reach some or all of the intended recipients.

Subject: Email subject
Sent: 8/14/2017 3:14 PM

The following recipient(s) cannot be reached:

'Recipient 1' on 8/14/2017 3:14 PM
This message could not be sent. Try sending the message again later, or contact your network administrator. The client operation failed. Error is [0x80004005-0x80004005-0x000501].

'Recipient 2' on 8/14/2017 3:14 PM
This message could not be sent. Try sending the message again later, or contact your network administrator. The client operation failed. Error is [0x80004005-0x80004005-0x000501].

The issue was the related to throttling settings, and the distribution list was over the 24-hour limit.

To fix the issue, you can create and apply a new throttling policy to the affected mailboxes:


New-ThrottlingPolicy -Name policyname -RecipientRateLimit Unlimited
Set-Mailbox -Identity username -ThrottlingPolicy policyname

Replace ‘username’, ‘policyname’, and ‘Unlimited’ with the desired names and values.