Migrating shared mailboxes and distribution lists

What replaces a shared mailbox in Google Workspace?

A shared mailbox becomes one of two things: a Google Group used as a collaborative inbox, or a delegated mailbox. Both let several people handle mail sent to one address such as info@ or support@. The right choice depends on how the address is used.

A collaborative inbox is a Google Group where members can see incoming conversations, assign them to each other, and mark them done. Groups do not need a paid license, which makes them a good fit for addresses that receive mail a team works through.

A delegated mailbox is a regular Google Workspace account that other people are given access to. Delegates open it from their own Gmail and can read, send, and organize mail on its behalf.

When should you use a delegated mailbox instead of a group?

Use a delegated mailbox when the address needs to behave like a full mailbox. That includes keeping a complete history in Gmail, using its own labels and filters, sending with its own signature, or holding years of migrated mail.

The tradeoff is cost and control. A delegated mailbox uses a license, and access is managed per delegate. A group is free and managed through group membership. Many organizations use groups for most shared addresses and a delegated mailbox for one or two that need a full mailbox, such as accounts@.

How do distribution lists move to Google Groups?

Each distribution list becomes a Google Group with the same address and members. People email the group address and every member gets a copy, just as before.

Groups can include other groups, so nested lists carry over. You can allow people outside the organization to email a group, or restrict posting to members only. Check this setting for every group that receives mail from customers or vendors. Mail-enabled security groups become groups too. Dynamic distribution lists that update membership from user attributes need a closer look, because you may need to manage that membership another way.

Our Premium plan includes setting up Google Groups as part of the migration.

How do you move the old shared mailbox history?

Old shared mailbox mail usually migrates into a licensed mailbox, which you then delegate to the people who need it. That keeps the full history searchable in Gmail.

Some migration tools can load history into a group's archive. Others cannot, or handle it differently. Confirm with your migration partner before you decide, especially if the history matters for customer service or records. If you only need the history for reference, one delegated archive mailbox is often simpler than splitting it across groups.

How do you avoid bounced mail at switchover?

Create every group and shared address in Google Workspace before you change your MX records. If an address does not exist in Google when mail starts arriving, senders get a bounce.

Before switchover:

• List every shared mailbox, distribution list, alias, and room mailbox in Microsoft 365.
• Create the matching group, delegated mailbox, or alias in Google.
• Allow outside senders on groups that receive customer or vendor mail.
• Set up "send mail as" in Gmail for people who reply from a shared address.
• Turn room and equipment mailboxes into calendar resources.
• Send a test message to each address and confirm it arrives.

The MX record cutover guide explains the switch itself. For what changes in each person's mailbox, see Outlook to Gmail: what changes for your users, and for the full project see the Microsoft 365 to Google Workspace migration guide.

Next step

We inventory and rebuild shared mailboxes, lists, and aliases before your switchover. See our Microsoft 365 migration service.