[imp] stupid icon question

[Rick Emery]

Here's a really stupid question. In the folder list, there is a graphic for each
folder. For most, it's a mail tray. Some are empty, some have a blue arrow
pointing away from the tray, and the INBOX has a red arrow pointing into the
tray. For a long time, I've wondered what the difference is between the empty
trays and those with the blue arrow. Can anybody tell me?

Thanks in advance,
Rick