In PowerShell, start an online session with the Exchange Online server using the following commands.
LiveCred = Get-Credential $Session = New-PSSession -ConfigurationName Microsoft.Exchange -ConnectionUri https://ps.outlook.com/powershell/ -Credential $LiveCred -Authentication Basic -AllowRedirection Import-PSSession $Session
Then create a new inbox rule to forward to multiple recipients by using the following command:
new-inboxrule -name "Forward to email@example.com and firstname.lastname@example.org" -mailbox email@example.com -redirectto firstname.lastname@example.org,email@example.com
Confirm that the inbox rule has been created
get-inboxrule –mailbox firstname.lastname@example.org
Out of courtesy, I perform a couple more steps. Sending an email to their personal email account to let the affected recipients know what has been done and to inform them that a test email will be sent to their Office365 email simply to verify that it actually forwards properly to their personal email.
Template of email to inform recipient that forwarding has been configured:
We have created forwarding rules for your Office365 email and will send a test message to email@example.com. This test message should appear automatically in your personal mailboxes (firstname.lastname@example.org and email@example.com)
Test email template:
Subject: Email forward confirmation requested
This email is to confirm that automatic forwarding has been set up on your Office365 email account to forward to your personal email account. Please reply as confirmation that you have received it.
There is no need to enter any correspondence in the body of the response email.