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Mailbox Delegation gives one person access to one or more mailboxes: full access to open them, or the right to send as or on behalf of them. Use it when someone needs to work from a colleague’s mailbox, for example while they’re away. It needs Microsoft 365 connected, with Exchange access for the client.

Mailbox Delegation in 50 seconds: what it asks, what it does and what you get.

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What the form asks

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What it does

  1. Creates a ticket in your PSA, if Ticketing is on.
  2. Waits for approval, if Approval is Internal or External, or a conditional override matches.
  3. Grant Mailbox Access: for each mailbox, in the client’s Exchange Online:
    • Full access lets the delegate open the mailbox, with auto-mapping if the form says Yes.
    • Send as lets them send mail that appears to come from the mailbox.
    • Send on behalf lets them send mail that shows it was sent on the owner’s behalf.
With Log actions to the ticket on, the ticket also gets a note when the run starts, after Grant Mailbox Access and when the run completes. Each run grants one access level. To give someone full access and Send as, run it once for each. Full access on its own doesn’t let them send from the mailbox. See Microsoft’s Manage permissions for recipients.

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Configure it

Go to Config, choose Mailboxes and click Mailbox Delegation.

Configure Mailbox Delegation: every option, step by step (1:25).

Approval, Ticketing and User directory filters are set on Base config and apply to every client unless you override them for one. For how Base config and client overrides work, see How configuration works.

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Troubleshooting

Check User directory filters. Shared mailboxes usually have no licence and leavers’ sign-in is blocked, so for that client override the filters and untick Licensed users only and Active users only.
Auto-map only applies to Full access, and only when the form said Yes. Outlook can take a while to pick it up; otherwise the delegate can open the mailbox themselves.
The client has no Exchange connection in Triggr yet. See Exchange Online.