Office 365 Send As Permission
You want to set up the ability to Send As a distribution group or as another user on your Office 365 account.
You must use the Power Shell. Here are the steps.
1. Start->type PowerShell in the search box -> right-click it in the list and choose Run As Administrator
2. Type in a,b,c,d commands as shown below.
a. $cred=Get-Credential (type in your account and password in credential window.)
b. $Session = New-PSSession -ConfigurationName Microsoft.Exchange -ConnectionUri https://ps.outlook.com/powershell/ -Credential $LiveCred -Authentication Basic –AllowRedirection
(type in your account and password in credential window again.)
c. Set-ExecutionPolicy Unrestricted
d. Import-PSSession $session
Add-RecipientPermission <identity> -AccessRights SendAs -Trustee <user>
For example, to give the user named Ayla Kol Send As permission for the Help Desk mailbox , run the following command:
Add-RecipientPermission "Help Desk" -AccessRights SendAs -Trustee "Ayla Kol"
Ayla can now send messages that appear to come directly from the Help Desk mailbox.