How did that 1.5GB message get into my Exchange environment anyway?

ISSUE: Recently, I had a customer call in an issue where their transport services were failing on all Exchange 2013 servers usually within minutes of each other. Transport would restart on its own and then 15 minutes to an hour later, they would crash yet again. The following errors were showing up in the Event…


Mail not routing to on-premise Exchange 2013 environment from O365 with 450 4.7.320 Certificate validation failed error

Issue: User is trying to send email from his O365 Tenant in to the OnPrem Exchange 2013 environment. The email fails with the following reason (as seen in the message tracking logs in O365: Reason: [{LED=450 4.7.320 Certificate validation failed};{MSG=SubjectMismatch};{};{IP=###.###.###.###};{LRT=4/14/2017 1:07:17 PM}]. OutboundProxyTargetIP: ###.###.###.###. OutboundProxyTargetHostName: Cause: We found that the certificate it was trying…


Email destined for recently moved Modern Public Folders are going to the Poison queue.

Scenario I recently worked a case where the customer had moved all of the public folders from one Modern Public Folder mailbox to another and deleted the old Public Folder mailbox. This was on Exchange 2013 CU9. After he did that, email destined for what were previously mail-enabled Public Folders started to show up in the…


1007 AccessDenied: Access Denied when trying to renew Federation Certificate

The 1007 AccessDenied event is usually tied to a time skew issue and that should always be confirmed before proceeding, however, that is also the error you will get when you try to renew a federation certificate in Exchange, when the old certificate has already exceeded the expiration date. Scenario I am trying to replace…


Unable to expand legacy onPrem Public Folders with O365 account

I have been seeing a few scenarios lately where users who log into Exchange using an account other than the OnPrem User Principal Name (UPN) are running into various difficulties. Today we will focus on one of those scenarios. We will discuss how we figured it out and what needs to be done to get the desired functionality….