Fixing Lost Gmail Delegation After Device Changes

Gmail delegation — letting one user read and send from another’s mailbox without sharing a password — is a workhorse feature in Google Workspace. It’s also one that quietly breaks after device changes, account migrations, or security-setting updates, usually with no obvious error. Here’s how to diagnose and fix it.

What “delegation” actually is

Mailbox delegation grants a delegate access to send and read on behalf of another account, managed under Settings → Accounts → Grant access to your account, or centrally via the Admin console. Because it’s tied to account trust relationships and organizational unit (OU) policy, changes to either side can sever it — often without notifying anyone.

The common causes

• Delegation disabled at the OU level. An admin policy change that turns off mailbox delegation for an OU immediately breaks existing delegations for users in it.
• The delegate was removed and re-added. Re-adding recreates the grant but can leave the delegate’s client caching a stale state.
• Security setting changes — enforcing 2-Step Verification or tightening less-secure-app access can interfere with how delegated sessions authenticate.
• Mail delegation confused with a shared/POP setup that was actually the thing doing the work.

The fix, in order

1. Confirm delegation is allowed for the OU. In the Admin console: Apps → Google Workspace → Gmail → User settings, find Mail delegation, and confirm it’s enabled for the affected organizational unit.
2. Re-establish the grant. Have the mailbox owner remove the delegate and add them again under Settings → Accounts and Import → Grant access to your account. Delegation can take up to 24 hours to propagate, but is usually much faster.
3. Have the delegate fully reload. The delegate should remove and re-add the delegated mailbox from their account switcher, then sign out completely and back in. Delegated mailboxes appear under the account menu, not as a separate login.
4. Check for conflicting security enforcement. If 2SV was recently enforced, confirm the delegate account is fully enrolled and compliant — partial enrollment can block delegated access.

Prevent the recurrence

Document which mailboxes have delegates and why. When you standardize offboarding and device-change procedures — the kind of continuous documentation we build for MSPs — delegation breakage stops being a surprise and becomes a checklist item.

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