Using Copilot on a Delegate Mailbox

Question

Using Copilot on a Delegate Mailbox

Jacobs, Mark 10

Microsoft recently announced support for users assigned "full delegate access" to use Copilot to search the contents of another user's mailbox. The article noted that:

User's image

My QUESTION is: What does "full delegate access" mean, specifically?

Can the mailbox owner simply go to File > Account Settings > Delegate Access and assign another person EDITOR (or) AUTHOR (or) REVIEWER (or) CONTRIBUTOR rights? Do any of these permission levels equal "full delegate access"?
If the permissions available under File > Account Settings > Delegate Access do NOT give the delegate "full delegate access"-- what is the SPECIFIC permission level within Exchange that a delegate would need? Is it "Full Mailbox Access (FMA)"?

Thank you for any assistance in clarifying this issue.

Yasser Mohamed 0 Reputation points

2025-12-18T16:27:13.56+00:00

did you find an answer to this question?
Jacobs, Mark 10 Reputation points

2025-12-18T16:50:55.4833333+00:00

@Anonymous YES. The answer is that granting Full Mailbox Access (FMA) via Exchange is the ONLY permission model fully compatible when a user wants to use Copilot to search a mailbox as a delegate.

NOTE 1: Even with FMA, users may still experience incomplete or negative search results if they reference a mailbox using Context IQ (e.g., /Smith, John) instead of the full email address (e.g., john.smith@microsoft.com) in the prompt. Until this is resolved, instruct users to always use the full email address followed by the word “mailbox” when referencing a mailbox in a Copilot prompt. (per this article)

NOTE 2: FMA grants access to all mailbox content, including private items. The mailbox owner should carefully weigh the trade-off between providing broad access and maintaining privacy.
Yasser Mohamed 0 Reputation points

2025-12-18T20:12:05.8133333+00:00

Thank you for sharing, very helpful!
PanK 0 Reputation points

2026-01-14T18:18:45.1233333+00:00

So Mark - you said

"The answer is that granting Full Mailbox Access (FMA) via Exchange is the ONLY..."

Question - how did you grant FMA to the delegate? What does EXCHANGE mean -through some admin setting

OR the screenshot above for Delegate Permission?
Jacobs, Mark 10 Reputation points

2026-01-14T18:25:08.5033333+00:00

By "Full Mailbox Access (FMA)"-- I meant assigning the permission directly on the mailbox through the Exchange admin tools—either in the Microsoft 365 Admin Center under Exchange Admin Center (EAC) or through PowerShell. “Exchange” in this context isn’t a separate app you need to look for; it’s the backend service that manages Outlook email, calendars, and mailbox permissions in Microsoft 365. So essentially, FMA is granted by going into the mailbox settings in the Exchange Admin Center and adding the delegate there.
PanK 0 Reputation points

2026-01-14T18:36:35.2366667+00:00

Got it. Thanks for a quick response.

So If I am delegating my mailbox to an EA - as a person delegating the mailbox access - I CANNOT do it (using the screenshot above). I will have to reach out to someone with admin access to (Exchange Admin Center) do it then.. right?
Jacobs, Mark 10 Reputation points

2026-01-14T18:57:06.2466667+00:00

RE: "I will have to reach out to someone with admin access to (Exchange Admin Center) do it then.. right?" -- YES, that is correct.
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This comment has been deleted due to a violation of our Code of Conduct. The comment was manually reported or identified through automated detection before action was taken. Please refer to our Code of Conduct for more information.

Your answer

Yasser Mohamed 0 Reputation points

2025-12-18T16:27:13.56+00:00

did you find an answer to this question?
Jacobs, Mark 10 Reputation points

2025-12-18T16:50:55.4833333+00:00

@Anonymous YES. The answer is that granting Full Mailbox Access (FMA) via Exchange is the ONLY permission model fully compatible when a user wants to use Copilot to search a mailbox as a delegate.

NOTE 1: Even with FMA, users may still experience incomplete or negative search results if they reference a mailbox using Context IQ (e.g., /Smith, John) instead of the full email address (e.g., john.smith@microsoft.com) in the prompt. Until this is resolved, instruct users to always use the full email address followed by the word “mailbox” when referencing a mailbox in a Copilot prompt. (per this article)

NOTE 2: FMA grants access to all mailbox content, including private items. The mailbox owner should carefully weigh the trade-off between providing broad access and maintaining privacy.
Yasser Mohamed 0 Reputation points

2025-12-18T20:12:05.8133333+00:00

Thank you for sharing, very helpful!
PanK 0 Reputation points

2026-01-14T18:18:45.1233333+00:00

So Mark - you said

"The answer is that granting Full Mailbox Access (FMA) via Exchange is the ONLY..."

Question - how did you grant FMA to the delegate? What does EXCHANGE mean -through some admin setting

OR the screenshot above for Delegate Permission?
Jacobs, Mark 10 Reputation points

2026-01-14T18:25:08.5033333+00:00

By "Full Mailbox Access (FMA)"-- I meant assigning the permission directly on the mailbox through the Exchange admin tools—either in the Microsoft 365 Admin Center under Exchange Admin Center (EAC) or through PowerShell. “Exchange” in this context isn’t a separate app you need to look for; it’s the backend service that manages Outlook email, calendars, and mailbox permissions in Microsoft 365. So essentially, FMA is granted by going into the mailbox settings in the Exchange Admin Center and adding the delegate there.
PanK 0 Reputation points

2026-01-14T18:36:35.2366667+00:00

Got it. Thanks for a quick response.

So If I am delegating my mailbox to an EA - as a person delegating the mailbox access - I CANNOT do it (using the screenshot above). I will have to reach out to someone with admin access to (Exchange Admin Center) do it then.. right?
Jacobs, Mark 10 Reputation points

2026-01-14T18:57:06.2466667+00:00

RE: "I will have to reach out to someone with admin access to (Exchange Admin Center) do it then.. right?" -- YES, that is correct.
Deleted

This comment has been deleted due to a violation of our Code of Conduct. The comment was manually reported or identified through automated detection before action was taken. Please refer to our Code of Conduct for more information.