Get Sendio Customer Review

I have been having problems with one particular user in Office 365 who could not send or receive emails and he was always getting the error that the email was not delivered due to the below error.

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 messages outside of your organization. Contact your email admin for assistance.

Diagnostic information for administrators:
Generating server: --------------.eurprd02.prod.outlook.com
Remote Server returned '550 5.1.8 Access denied, bad outbound sender'

The problem is that the email was being blocked by Microsoft due that 5000 emails have been sent by the mailbox. The problem is not that your mailbox was hacked, but that the email header was spoofed by someone. To check that the mailbox is being blocked, open the Exchange Admin Center in your Office 365 portal, click on Protection and on Action Center.

Original article can be found here

Watch it on Youtube: Get Sendio Customer Review

1 2 3 4 7,104