When you are reading an old message, and a new message arrives, you are moved to the new message, which is very annoying. (see above)
Further, it would be great, if you take a trade, attached to a message, that you do not end up at the newest message, but stay at the position of the trade(s). It is annoying if you have to croll upwards all the time if there are several trades to be taken.
So, just "fix" the position in a mail to where your present position is, no matter what comes in. When the mail is closed, return to the latest mail (remove temporary fixing).