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 noreply@smtpdomain.com. 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 noreply123@smtpdomain.com, 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.