Office 365 Mail flow & shared mailboxes.  Learn to redirect emails, add other transport rules & save on mailbox licensing.

Office 365 Mail flow & shared mailboxes have a lot of lingo being tossed around.  IT resources on the inter-webs throw out the expression Transport Services on top of it and your head is spinning.  Don’t worry we break it down to the bare essentials so you can improve your organizations workflow, maybe solve a couple IT puzzles, and have that amazing aha moment when you found a solution that’s been bugging you.  We will help connect connect the dots where Shared Mailboxes come in handy with email redirects in the transport rules section of Exchange.

What are Shared Mailboxes?

Shared mailbox allow you to save money on mailbox licensing for Office 365 or Microsoft Business 365 as Microsoft now brands their suite of services after April 2020.  For instance, every user typically has there own mailbox but they may also need to manage an Accounts Payable mailbox, Accounts Receivable, a customer support mailbox, etc.  These additional shared mailboxes are free as long as the user’s mailbox is a member of these shared mailbox. (user mailbox)

Transport Service is where Mailflow resides in Office 365 Exchange

We will show off a couple mailflow can do before getting crazy with the lingo.  By definition, the transport pipeline is a collection of services, connections, and components, and queues that work together to route all messages to the categorizer in the Transport services on an Exchange Mailbox server inside the organization.  Want to nerd it out more?  Defer to Microsoft docs for more details.  Have some specific goals in mind for processing email, stick around here.

Exchange Admin Portal

Want to block or delete an external email from coming into your organization?

Got a spammy vendor?  Here are the steps to block or delete their email from your organization.  In this case, we blocked Webroot marketing email since their unsubscribe feature does not work.

Office 365 Mail flow & shared mailboxes





I circled all the options necessary to get your new rule up and running.  Though, applying the block to an external email can be a bit confusion for first time setup.  See the next illustration for where to add the external email address.

Office 365 Mail flow & shared mailboxes

Add external email to transport rule.














Avoid Office 365 licensing and have your incoming email redirect to an external email like FreshDesk

Note:  This is different than placing a forwarder on emails.

You are Acme Org.  You have an email  You wish to take a third-party platform to not only be you incoming email by company but maybe provide a ticketing system.  Every dollar counts at  Office 365 Mail flow & shared mailboxes require a specific steps performed first.  Setup a shared mailbox as discussed above first.  Then setup a redirect in the Mail Flow section of Office 365 Exchange.  Head over to the Exchange Admin Center:


Transport Rules











Remember to that Office 365 Mail flow & shared mailboxes require certain steps to be in order if you want email redirected to an external email address. Head back to the “dashboard” if you have not created a Shared Mailbox first.

Office 365 Mail flow & shared mailboxesOffice 365 Mail flow & shared mailboxes








Office 365 Mail flow & shared mailboxes Summary


I will continue to add cool Mailflow tricks as I see fit.  Mailflow and Shared Mailboxes will become your best friends for preventing your organizations data from being compromised, savings on licensing, and a whole lot more.


Additional Resources:

Redirect Support Emails in G-Suite for the Autotask Email Processing Best Practice

Office 356 Outlook Mobile Email & Webmail Setup

Leave a Reply

Your email address will not be published. Required fields are marked *