You can read postal codes in SwissSalary BAU/NAV under Setup –> Generally –> ZIP Codes.
The following window appears:
Click this icon (hyper link) to open MAT[CH] website: http://www.post.ch/en/post-startseite/post-adress-services-match/post-direct-marketing-datengrundlage/post-adress-services-downloadcenter.htm. Click Postcode Plus 1: on the home page (see image below)
Save the zip file to a drive, e.g., on the desktop or in My Documents.