So you are in a hybrid environment and moved your Public Folders to o365 but suddenly 3rd party people can no longer send you emails?

Yeah… try this:


Trying to block zip files with O365 seems a little painful, as the default GUI does not really give you the option (anymore?) If you Google, you might find screenshots with options to select the attachment but when I checked our GUI, that was all that I saw:

Clearly, there is no option to look for attachments, other than what the attachments CONTAIN.

So, trying PowerShell, something interesting happened.

Executing this PowerShell command, it created a new rule, that now had more/different options than the rule you could create from the GUI!

Look at this:

And now you can block file extensions and stuff to your heart’s content.

Oddities ¯\_(ツ)_/¯

We had a $user who deleted ALL emails from a shared mailbox and you might notice that the option to recover deleted items is grayed out and you cannot select it.

We need to set a registry key to turn that option on.

Create a new DWORD value with the name ‘DumpsterAlwaysOn’ and a value of 1.

Easy via PowerShell:

You have to close Outlook and start it again and voila, you can restore items.


Want to use PowerShell on your CentOS box? Easier than ever!