I just received a PM and I was at bay where to find it. It was at the bottom of the inbox which I feel is the reverse of how it should. May be just me. But please do give a look. Thanks. :)
The default setting seems indeed to be "off", but probably on would be better.
You can change it in the pm settings though with "Show most recent personal messages at top". :D
No offence, I guess other way would have been nice.
https://github.com/emanuele45/Dialogo/commit/660978952b4924e02ac64184253b363a35441496