When I reply to a message, it doesn’t display (quote) the original message?

If the message you are viewing is an HTML formatted message that does not include a “plain text” version then when you go to Reply there will not be an original message because Runbox only uses the “plain text” version for the Reply.

The behavior is typically seen with HTML messages sent from Hotmail because Hotmail doesn’t include a “plain text” version with the HTML message.