Not able to provide send as permission to a shared mailbox, getting the below error, tried via Powershell and GUI both

Question

Hello Team,

I am not able to provide send as Access to recipients to a shared mailbox and getting the below error

PS C:\Users\nilay.bhoraskar> Add-RecipientPermission "sesizari.distribuitori_externi@X .com" -AccessRights sendas -Trustee "Luiza-paula.robu@X .com"
Creating a new Remote PowerShell session using Modern Authentication for implicit remoting of "Add-RecipientPermission" command ...

Confirm
Are you sure you want to perform this action?
Adding recipient permission 'SendAs' for user or group 'Luiza-paula.robu@X .com' on recipient Identity:'sesizari.distribuitori_externi@X .com'.
[Y] Yes [A] Yes to All [N] No [L] No to All [?] Help (default is "Y"): y
WARNING: An unexpected error has occurred and a Watson dump is being generated: Length of the access control list exceed the allowed maximum.

Length of the access control list exceed the allowed maximum.

• CategoryInfo : NotSpecified: (:) [Add-RecipientPermission], OverflowException
• FullyQualifiedErrorId : System.OverflowException,Microsoft.Exchange.Management.RecipientPermission.AddRecipientPermission
• PSComputerName : outlook.office365.com

I checked and tehe mentioned shared mailbox has 1048 recipients added for Sendas permission and 899 for Full accesss permission, I was able to provide Full access permission without any error.

Is there any limit on the Delegate access for a user/shared mailbox because I didn't find any public article for the same.

requesting your help on this.

Also attaching the GUI screenshot for reference.

]1

Answer 1

Yea, maybe nothing official but that error is pretty explanatory. There is always a maximum limit even if its not documented.
Typically its around 1000 entries or so.