A user is receiving workflow notification emails such as Content Approval ones that contain an invalid link to the page. On further inspecting, the link/URL is using the Portal Alias from another site in the installation.
One reason for this to occur is when the affected Portal is part of a Site Group. The current behavior is that the Portal Alias from the Master Site will be used as the base URL for the workflow notification for all other sites in the group which might result in a broken link.
This behavior is currently being updated by our team so each site in the group uses its own Portal Alias for the workflow notifications. The fix is planned to be released in version 9.10.4 and once available Upgrading your DNN instance to the latest version would resolve the issue.
DNN-59611 - Expected to be released as part of the 9.10.4 release.
In the meantime, a possible workaround for this issue would be to update the affected portal to be the Master Site of the group; nevertheless, note that all other sites on the group would be using this new Portal Alias for the notifications.