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Unlike Microsoft 365, Google Workspace has no shared mailbox concept. When a user’s data needs to be split among multiple successors, the migration tooling falls short — this runbook covers a reliable alternative approach.

Requirements

This can all be done with the user account suspended.

Mailbox Data Handling

1. Create a group mailbox

With these properties you’ll establish a good and scalable precedent.
PropertyConventionExample
NameOffboarded User - [User Full Name] (email_prefix) - YYYY-MM-DDOffboarded User - John Smith (john.smith) - 2023-01-01
Addressoffboarded_[emailprefix]@domain.tldoffboarded_john.smith@domain.tld
Group OwnerYou
PermissionsSet everything to “Owner”

2. Back up the user’s mail with gyb (messages under 25 MB only)

Substitute john.smith with the offboarded user’s address prefix and you with your admin address:
gyb --email john.smith@domain.tld --action backup --service-account --search smaller:25M
This exports each message to .eml format in a structured directory, along with an SQLite database tracking message metadata.

3. Restore the backup to the group mailbox

gyb  --action restore-group --email offboarded_john.smith@domain.tld --use-admin you@domain.tld --service-account --local-folder /PATH/TO/BACKUP/DIR
Restoration is rate-limited to approximately one message per 1.5 seconds — this is a Google API constraint.

4. Take a full backup of the user’s mailbox (all sizes)

gyb --email john.smith@domain.tld --action backup --service-account

5. Archive the mailbox and store it in a Shared Drive

Using ZStandard compression saves significant space and is faster than gzip. Requires zstd in your PATH.
tar -acvf john.smith.tar.zst GYB-GMail-Backup-john.smith\@domain.tld/

6. Remove yourself as owner of the group mailbox.

7. Add the users inheriting this data as “Contributors” to the mailbox.


Drive Data Handling

If after this the user’s account still shows drive storage quota being used, it’s likely they have backed up their computer directories using the Google Drive desktop app. See the troubleshooting page for a fix.

1. Create a Google Shared Drive for the offboarded user

PropertyConventionExample
NameOffboarded User - [User Full Name] (email_prefix) - YYYY-MM-DDOffboarded User - John Smith (john.smith) - 2023-01-01
AccessYou + Offboarded User added as Managers
gam user you@domain.tld create teamdrive "Offboarded User - John Smith (john.smith) - 2023-01-01" adminmanagedrestrictions true asadmin
Be sure to grab the Teamdrive ID — it’s a string of random characters output after the generation.

Add the offboarded user as a manager

gam add drivefileacl TEAM_DRIVE_ID_HERE user john.smith@domain.tld role organizer

2. Move Data from the user’s “My Drive” to the “Shared Drive”

This will retain all document-level IDs and sharing settings, though you will lose directory-based sharing (i.e. if the user shared a whole folder, that access will be lost).
gam user john.smith@domain.tld move drivefile root teamdriveparentid TEAM_DRIVE_ID_HERE mergewithparent duplicatefolders merge createshortcutsfornonmovablefiles

3. Set access

Remove yourself and the offboarded user as managers. Add any users who need the data as contributors — keeping access at contributor level encourages working in Shared Drives rather than private storage.
If drive storage quota still shows usage after emptying the offboarded user’s drive, see Transferring ownership of orphaned files.