I rarely venture onto gmail's webmail pages instead preferring to use my desktop email client (in my case Apple's Mail).

Within Mail (and presumably most if not all email clients on MacOSX, Windows and other platforms) there is an option to mark emails as Low, Normal or High Priority (or equivalent wording) but I cannot find any option to mark emails thus when logging onto and composing via the gmail webmail page.

Is that facility not possible on the webpage or am I being stupid and overlooking the bleeding obvious?

And if the latter, how can i do it?

Many thanks in advance.