If your Exchange system allows spoofing, you can do it with PoliteMail, but generally these get blocked/rejected, as email spoofing is seen as more of a security risk than not. If you set PoliteMail to send via the Server (not the Outbox), enable tracking, and click the Outlook From button, select other email address, and send from, “Santa Claus email@example.com” the email will go through (if your Exchange system allows it). In the same way, you would select another user within your organization and send from that person (again, if your Exchange configuration allows it).
Note that if you use that method to just change the from display name, “Santa Claus firstname.lastname@example.org” on receipt, Exchange/Outlook will display the name Exchange has associated with that mailbox, so your own name not Santa.
Any one Outlook user can send from multiple mailboxes. Using Exchange shared mailboxes, several communications senders could send from the same shared mailbox address, or multiple shared mailboxes they are given permissions for. This is a common approach for managing executive communications, where a shared mailbox is created under that executive's name, but with a different mailbox address than their personal account. This mailbox might be shared with the executive’s assistant and some comms team members. Any one of those people could access that shared mailbox in Outlook and send email from that address with both replies and auto-replies coming back to the shared mailbox, not the executive's personal mailbox.
Also, Exchange users are not limited to one email address. An Exchange admin could set up multiple addresses for a communications user, so they could send from and receive email to their inbox from these additional addresses.
PoliteMail also supports send-from permissions, such that any number of PoliteMail users can request permission to send from another’s email address. Once the recipient authorizes permission using an email loop, that user can send from that address. This is less ideal and popular than the shared mailbox concept, and both can also be used in conjunction.