To change a URL after a tracked message has been sent:
Navigate to Outlook > Politemail > Content > Links
Select the Link
Select the Edit button
Scroll to the URL column and make any necessary changes by clicking into the field and editing the existing link.
Select Update to save the change.
Any recipient that opens or re-opens the email and clicks on the link will be brought to the revised URL location.
Note: This process should only be used for typed URLs and hyperlinks within a sent message, not smart attachments or image reference links. To change Smart attachments or image references for a sent email see this article.