I too am used to seeing newest replies on top, oldest replies on the bottom, the same chronological order I use for my Inbox sorting.

I can't seem (or see how) to change this when viewing threaded emails AKA Conversation Grouping.

This is nearly three years old, any possibility of having this added?

I wuold like to have an option in " appearence > conversation grouping " from settings page that enabe most recent received email to be on top of the scroll - others messages should follow scrolling down to the older one

Xav's css works well in chrome, less so in firefox

Yes, please implement this asap. Also conversation grouping on mobile apps please!

I was looking for a way to do this, and a bit of CSS is enough.
Go to Settings > Appearance, and in the field "Custom Theme" add this :

/* Reverse messages sorting of conversations */
#pm_thread {
display: flex;
flex-direction: column-reverse;
}

I second this request

I would be great to have it.
Currently I have conversation with > 10 messages and it gets bigger and bigger. Every time I want to see update I have to scroll to bottom to see most recent mail.