In a late afternoon Pos Malaysia e-announcement, the International Definitive Stamps are now applicable for Domestic Mail.
Previously the International Definitive Stamps were only allowed for International Mail as local postage was subjected to GST. With this restriction lifted and currently no GST on domestic mail, the International Definitive Stamps can now be used for local mail.
Since the notice is short, it is time to quickly get to the nearest post office, if you want to get at least a 30 October 2018 mailed postmark or a registered mail.
ps: Thanks to a reader for pointing out my year was ahead in 2019! It should be 2018. I was rushing this post out before it is too late.