Enable Forwarding on a User Mailbox as an Admin

As the admin of an Office 365 organization, you might have company requirements to set up email forwarding for a user's mailbox. Email forwarding lets you forward email messages sent to a user's mailbox to another mailbox.

How to Enable Forwarding on a User Mailbox
  1. Sign in to Office 365.
  2. Click on the admin app tile.
  3. Select Users > Active Users
  4. On the Active users page, choose the user who's email you want to forward.
  5. Scroll down to Mail Settings and expand using the drop-down. Click or tap Edit next to Email Forwarding
  6. On the Email forwarding page, select Forward all email sent to this mailbox toggle, enter the forwarding address, and choose whether you want to keep a copy of forwarded emails. If you don't see this option, make sure a license is assigned to the user account. Choose Save.
  • To forward to multiple email addresses, create a distribution list, and then set up forwarding to point to the DL's address using the instructions in this article.

  • Once you set up email forwarding, only new emails sent to the from mailbox will be fowarded.

  • Email forwarding requires that the from account has a license. If you're setting up email forwarding because the user has left your organization, another option is to convert their mailbox to a shared mailbox. This way several people can access it. However, a shared mailbox cannot exceed 50GB.

Resources:
https://docs.microsoft.com/en-us/office365/admin/email/configure-email-forwarding?view=o365-worldwide