Working with a Shared Mailbox

Benefits of Shared Mailboxes

A shared mailbox is essentially an Exchange Online mailbox without a license. Not having a license for Exchange Online comes with certain limitations:

• Shared Mailboxes cannot utilise Microsoft’s Advanced Threat Protection.
• Shared Mailboxes are intended to be used by individuals with Exchange Online licenses.
• Sign-ins on Shared Mailboxes are specifically blocked; access is granted to individuals with Exchange Online licenses as needed, with a limit of 25 users accessing a shared mailbox concurrently.
• Shared Mailboxes are still covered by the Anti-phishing and Anti-spam policies provided in Defender for Office 365.

Note: to work with Shared Mailboxes your Microsoft 365 Admin will first have to create the Shared Mailbox and delegate access to the appropriate licensed users… 

Shared Mailboxes and Security

A security best practice is to block sign-in for shared mailboxes to prevent brute force attacks on their static passwords as two-factor authentication is not an option for them.

It is advisable to acquire an Exchange Online Plan 2 license for sensitive 'shared mailboxes' like sales@, finance@, accounts@, etc. This license provides features such as litigation hold, in-place archiving, and additional storage capacity exceeding 50GB.

Licensing the Shared Mailbox still allows it to be delegated to other users and treated the same as regular Shared Mailboxes.

How do I access a Shared Mailbox ?

It’s quite easy, here we will outline the most common ways…

Shared Mailbox Access via Outlook Mobile App

The Outlook mobile App (for Apple/iOS and Android) supports Shared Mailboxes.

You add them the same way as you do other mailboxes and if you have rights to the shared mailbox you won’t need the password…

Open Outlook on your mobile (phone or tablet) and go to settings where you will see something like this. Click Add Email Account and choose Add Shared Mailbox to be prompted to choose the shared mailbox.

Simply complete the email address of the shared mailbox you need, click "Add" to add it to your Outlook Mobile App:

Shared Mailbox Access via Outlook Web Access

Often the most convenient, simply open our Outlook Web Access (OWA) and click your name and then click open another mailbox:

In the Open another mailbox dialog box just start typing the name of the shared mailbox, office will auto prompt so you can select it from a list… when you see it click on it and it will open in a new tab right in your browser.

Shared Mailbox Access via Outlook Desktop App

An Admin can delegate a shared mailbox to you such that it will add itself to your Outlook Desktop App automatically, you won’t have to do anything to activate it but it may take up to an hour to appear. For instant access you can use the Outlook Web Access option above until the mailbox appears in your Outlook Desktop App. This is known as "automapping" and is generally not recommended as the shared mailbox by default will merge into your OST and could cause issues with the file size of the OST file and may also cause search issues. 

We can delegate the Shared Mailbox to you without AutoMapping still allowing you easy access via webmail and Outlook Mobile but without the other downsides.