Hi there,
If you are planning to automate the process of mailbox delegation you can try it out with tools like Taskscheduler or Powershell.
In Exchange Server, you can use the Exchange admin center (EAC) or the Exchange Management Shell to assign permissions to a mailbox or group so that other users can access the mailbox (the Full Access permission).
Use the Add-MailboxPermission cmdlet to add permissions to a mailbox or to an Exchange Server 2016, Exchange Server 2019, or Exchange Online mail user.
Add-MailboxPermission https://learn.microsoft.com/en-us/powershell/module/exchange/add-mailboxpermission?view=exchange-ps
Manage permissions for recipients in Exchange Online https://learn.microsoft.com/en-us/exchange/recipients-in-exchange-online/manage-permissions-for-recipients
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