Overview
When sending an email message you may receive a Non-Delivery Report (NDR), also known as a "bounce message", that has this information displayed:
Delivery has failed to these recipients or groups:
recipient@email.address
Your message couldn't be delivered because you weren't recognized as a valid sender. The most common reason for this is that your email address is suspected of sending spam and it's no longer allowed to send email. Contact your email admin for assistance.
There will be addition information in the "Diagnostic information for administrators"
Remote Server returned '550 5.1.8 Access denied, bad outbound sender AS(42004)'
Here is an example message in Outlook web:
Resolution
The university restricts outbound email delivery to 500 recipients per message, 500 recipients per-hour and 1,000 recipients per-day for employees.
- If you are sending a message to a small number of recipients you may have hit the per-hour recipient limit
- Action: Wait 1 hour before re-sending the message.
- If you are attempting to send a mass mailing, or send to a large email group, you may have hit both the per-hour and per-day sending limits.
- Action: Wait 1 hour and resend to a portion of your list or Contact University Communications and Marketing for bulk-mail delivery assistance.
- If you are attempting to send a mass mailing as a single message to more than 500 recipients, you may have hit the 500 recipients per message limit.
- Action: Wait 1 hour and resend the message to 500 or fewer recipients at a time or contact University Communications and Marketing at ucm-web-admin@uidaho.edu for bulk-mail delivery assistance.
Warning
This bounce message may also occur when an account is compromised or Microsoft's risk tools determine the account is sending spam. This can result in the account being added to a blocked sender list. When this occurs, the account will have to be removed manually from the block list.