Kmail, Thunderbird, Evolution. That’s pretty much it.

There’s always some weird niche client somewhere but it won’t be a hidden gem. Although I guess you can always use Pine (or rather Alpine nowadays) if you want to appear ubergeeky.

Look at the properties of the file in dolphin. It will show you various file signatures.

Isn’t the problem that it’s blocked by a number of patents, or something like that?

Because when there’s a new hardware function, the driver has to add support for it.

My only currently active machine is a laptop named buttwarmer as per my cat’s suggestion.