Using a "Shared Mailbox"

Question

Using a "Shared Mailbox" with an alias of *****@companyname.com be shared with gmail addresses?

Answer 1

Dear Joe,

Good day, and thank you for reaching out to the Q&A Forum. To answer your question directly: no, a Gmail address cannot be added directly to a Shared Mailbox. From my research, only people inside your organization can use a shared mailbox, and you cannot give people outside your business (such as those with a Gmail account) access to your shared mailbox. This is exactly why the picker only shows your company addresses and will not let you type in a Gmail address. The good news is that there are a couple of supported alternatives, depending on what you are trying to achieve.

Option 1: Create a Microsoft 365 Group

Unlike a Shared Mailbox, a Microsoft 365 Group for Outlook does support external (guest) members, so you can add Gmail addresses. Guests can:

• Receive emails sent to the group address.
• Reply to and participate in group conversations.
• Access shared files in the group, depending on the permissions you set.

Please note that guests will reply from their own Gmail address rather than as the company address. So if sending as ******@companyname.com is a hard requirement, this option will not cover that.

Option 2: Create a Microsoft 365 account for them

If the person genuinely needs to read, reply, and send as the company address through the Shared Mailbox, the only supported way is to create a Microsoft 365 user account for them on your domain and assign Shared Mailbox permissions to that account. Note that the Shared Mailbox itself does not require a license (up to 50 GB), but each user accessing it must have their own Microsoft 365 license with an Exchange Online plan.

Option 3: Forward or use a Distribution List (receive-only)

If the Gmail users only need to receive the emails and do not need to reply as the company address, you can:

Create a mail contact for the external Gmail address in the Microsoft 365 Admin Center (Users > Contacts > Add a contact). Add that contact to a Distribution List, which does support external members.

Alternatively, you can simply set up mail forwarding on the Shared Mailbox to forward incoming messages to the Gmail address.

For reference:

• About shared mailboxes in Microsoft 365 | Microsoft Learn
• Create a Microsoft 365 group in the admin center | Microsoft Learn
• Create a shared mailbox | Microsoft Learn
• Add users or contacts to Microsoft 365 distribution list groups | Microsoft Learn

I hope this information helps clarify the situation and provides you with workable solutions. Should you have any further questions or need additional assistance, please don't hesitate to reach out. I'm always happy to help. Have a wonderful day! 

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