The listing of emails received shows blue and purple arrows pointing in different directions. What do these signify? I can't find a 'key' to explain.
The inbox for each of my accounts shows blue and purple arrows pointing in different directions. What do these signify and where can I find a key to explain all these various symbols which Thunderbird uses.?
Todas as respostas (1)
They are not well documented and tend to vary with platform, version and theme.
In short, those blue and purple ones indicate replied or forwarded messages.
There is a somewhat dated list here:
http://kb.mozillazine.org/Icons_-_Thunderbird_2
Even if that doesn't match exactly what you have, it should give an idea of the scope.
There is an assumption that these are all self-explanatory and intuitive, and hence don't need any documentation. ;-)