How to convert user mailbox into shared mailbox in office 365?

I'd like to share how to convert user mailbox into shared mailbox in office 365 today.

But before going through, let me explain briefly what is shared mailbox and what can we use it for.

A shared mailbox is a mailbox that multiple users can open to read and send e-mail messages. Shared mailboxes allow a group of users to view and send e-mail from a common mailbox. They also allow users to share a common calendar, so they can schedule and view vacation time or work shifts. Why set up a shared mailbox?

It can provide a generic e-mail address, such as or, which customers can use to inquire about your company.
It allows staff in departments that provide centralized services to employees, such as the technical support, help desk, human resources, or printing services, to respond to employee questions.
It allows multiple users to monitor and reply to e-mail sent to an e-mail address, such as a Technical Support , Help Desk, Customer Support.
In a school environment, it provides students and parents with an entry point to different school departments, such as academic departments, library services, or financial aid.
Shared mailboxes in Microsoft Office 365
In Office 365, shared mailboxes don’t require a license. However, each user who accesses a shared mailbox must have a user subscription license. Users with Exchange Online Kiosk subscriptions can’t access shared mailboxes. Also, shared mailboxes can’t be used to archive e-mail, except for the messages that are actually sent to or received from the shared mailbox.

Shared Mailbox Size can be 2GB to 5GB as shown in below link

But Office 365 recently upgraded and I was noticed that Shared Mailbox size become 25GB.

OK. Now I assume you guys know about Shared Mailbox in brief.

Let's start to convert user mailbox into shared mailbox now.

For example, I'll use below steps to do.
- First, convert regular mailbox of into shared mailbox.
- Second, grant access permission (Full and Send As) to shared mailbox for
- Last, revoke the subscription license of

First, Run Powershell as Administrator and login to Exchange Online.
Copy and Paste following command line by line into Powershell window.

Set-Mailbox -Identity "Technical Support" -Type “Shared”  
Set-Mailbox -Identity -Type “Shared”  - (To convert Technical Support Mailbox from Regular Mailbox into Shared Mailbox)

Add-MailboxPermission "Technical Support" -User "Tech Support 1" -AccessRights FullAccess
Add-MailboxPermission -User -AccessRights FullAccess - (Giving Full Access Permission to Tech Support 1 to access Shared Mailbox)

Add-RecipientPermission "Technical Support" -Trustee "Tech Support 1" -AccessRights SendAs 
Add-RecipientPermission -Trustee -AccessRights SendAs - (Giving Send As Permission to Tech Support 1 for Shared Mailbox)

Just press Enter when you see below prompt.
Are you sure you want to perform this action?
Adding recipient permission 'SendAs' for user or group 'Tech Support 1' on recipient 'Technical Support'.
[Y] Yes  [A] Yes to All  [N] No  [L] No to All  [?] Help (default is "Y"):

Login to Office 365 Portal. Go to Users and Groups>Active Users.
Choose Technical Support and Revoke subscription license.

That's it. Converting Regular Mailbox into Shared Mailbox is done.

In above example, you can modify highlighted text as your requirement. Text can use Display Name or Full Email Address.
Take note the doube quote of highlighted text. Double Quote is no need if your text is without space.

May you all be happy.
(Be knowledgeable, pass it on then)


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