Where are all expats? (I mean, Online)

A lot!

Facebook Groups (Expats in Vietnam, Expats in HCMC, Hanoi Massive...), Saigoneer,...

In case you are thinking of contacting them personally just to be polite and sincere enough, let me share my case! We are working on our local search app (Clingme), and one of our approaching method is to contact expats and foreigners via messages, to share with them the app and tell them how it may be of help to them. The app can guide even Vietnamese and foreigners on searching for places (restaurants, ATMs, pharmacies, bars...). I do think, it is useful enough to be shared. And I don't feel guilty at all when I want to contact them. But here are some responses I get:
1 - "F*** off"
2 - "W** "

I do expect that this is like "once in a lifetime" It was just my bad luck to encounter those expats and luckily the rest are so nice to us. Anyways, please avoid this channel because it may not be working for sure!

Sorry if this may be out of your concern!