Outbound emails from one specific email address blocked by Exchange 2013

Question

Hi
We have a hybrid environment Exchange Online and are using Exchange 2013 as hybrid server. We have an application that submits emails to Exchange using SMTP and sends emails from [email protected] Since almost half of our user base is already in Exchange
Online, many of these emails which are generated on-premises need to be routed to Exchange Online. This configuration has been working for months. On 24/06/2014, the emails from this application stopped getting delivered. 
On examination of message tracking logs, I found SMTP FAIL events - excerpt below.
ConnectorId             : Outbound to Office 365
Source                  : SMTP
EventId                 : FAIL
InternalMessageId       : 39560943768623
RecipientStatus         : {[{LRT=};{LED=550 5.1.8 Access denied, bad outbound sender};{FQDN=};{IP=}]}
Doing a search for the error in recipient status did not return anything but doing a search for "access denied, bad sender" did return results that suggested a scenario when a user in Exchange Online would be prevented from sending outbound email
after having been identified as sending spam - see http://technet.microsoft.com/en-GB/library/dn458545(v=exchg.150).aspx
It seems our on-premises Exchange 2013 server has enacted a similar block on our noreply address which sends out a lot of emails. I have been able to confirm that if the 'from address' is changed to something like [email protected], all emails from
the application get delivered successfully.
I now need to find out how I can unblock our noreply address so these emails can be sent with the original from address.
Appreciate all help I can get on this one.

Answer 1

Hi,
From your description, only one email address can't send messages from the application server. I recommend you check if there is any transport rule on Office 365 blocking this problematic email address.
What's more, please check your outbound spam policy, verify if there is any policy blocking this problematic email address.
For more information, here is a thread for your reference.
Configure the outbound spam policy
http://technet.microsoft.com/en-us/library/jj200737(v=exchg.150).aspx
Hope it helps.
Best regards,
Amy Wang
TechNet Community Support