If you look in the folder of the latest Singapore map you will see a postal_SGP.ttd file. This is a postcode file identical to the Singapore.postal file found in the zip folder. You would assume as it is in the map folder then it is used and the one in the zip folder is now redundant.
The other country postcode files 'postal_GBR.ttd' and 'postal_NLD.ttd' are not found in the nav2 map folders but can be found in nav3 map folders.
Doing a file compare of the 1025 versions of the *.ttd file (map folder) and the *.postal file (zip folder) shows they are identical.
\map\postal_GBR.ttd = \zip\Great_Britain.Postal
\map\postal_NLD.ttd = \zip\Nederland.postal
\map\postal_SGP.ttd = \zip\Singapore.postal
edit the *.ver file to show the correct version.
If tomtom doesn't fix its links with the correct files then I do have a set of *.zip files with the latest 1030 postal files ready to attach if needed