If you are forwarding to external domain ( not part of primary domain ) , please login to office 365 admin and add contact first. Then you can select the email on mail rules.
Add External Email to Contacts
- Log in to the Microsoft Exchange Admin Center, with your Office 365 email address and password.
- Under Recipients, click Contacts.
- In the contacts list, click the plus sign button, and click Mail contact.
- In the new mail contact dialog box, enter the information about the shared contact, and click Save
Exchange Online MAIL FLOW SETTINGS
1. Log in to Microsoft Office 365 using the administrator account.
2. From the top menu select Admin > Exchange to open Exchange Admin Center.
Configuring Forwarding Rule in Microsoft Office 365
3. Select mail flow to create the Forwarding/BCC rule.
4. In the rules tab, select the + (New) and select create a new rule.
Creating a new Forwarding Rule
5. In the new rule screen, configure the following options:
Name
| Type in a rule name, for example, Forwarding/BCC .
|
*Apply this rule if...
| Select [Apply to all messages] from the drop down list.
|
*Do the following...
| Select Bcc the message to... and select the journaling mailbox from the list of users that pops up.
IMPORTANT
If using a third party mailbox, select the appropriate user from the list.
|
Apply the new rule to all future messages
6. When prompted with the warning: Do you want to apply this rule to all future messages?, click yes.
7. Click save.
Verify configured Forwarding/BCC rule details
8. View and verify the configured Forwarding/BCC rule.