Office 365: Stop One User Sending Attachments

KB ID 0001544

Problem

If you have one, (or more) users and you want to BLOCK those users from sending ANY email attachments, here’s how to do it;

Solution

Log into your Office 365 tenancy with administrative access > Admin > Admin Centers > Exchange Admin > Mail Flow > Rules > Add > Filter Message By Size.

Name: Give it a sensible name.
Apply This Rule If: The message size is greater than or equal to = 1.00 KB (we will change this in a minute!)
The Sender Is: Add the user(s) in question.
Do The Following: Reject the message with the explanation = “Enter some sensible text”.

Scroll down.

Tick: Stop processing more rules.

Save.

Now this blocks all attachments over 1KB (1024 bytes), but this still lets a user send a smaller attachment! The ONLY way to fix that, is to drop the limit using PowerShell.

Connect to Office 365 Exchange PowerShell

Then use the following syntax;

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Set-TransportRule -Identity "Name" -AttachemtnSizeOver 1B

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Related Articles, References, Credits, or External Links

NA

O365: Enable Application Impersonation

KB ID 0001449

Problem

While using a migration tool to do some ‘on-prem’ to Office 365 migrations I had to enable ‘Application Impersonation’ for my Office 365 user. The tool didn’t explain how to do that, so I had to work it out for myself 🙁

So to make things easier for everyone else, here’s how to do it.

Solution

From within the Office 365 portal > Admin > Exchange.

Dashboard > Permissions > Admin roles.

Give the role a name/description e.g. Application-Impersonation (I hate spaces!) > Then Add the ApplicationInspection role, (seems the developers at Microsoft also hate spaces!) > OK.

Scroll down to ‘Members‘ and add in the user you want to allocate this role to > OK > Save.

Related Articles, References, Credits, or External Links

NA