There would be a small icon at the far LEFT of the account name (similar to the unread count icon at the far right) that looks like a little brown square folder, and is always present. Tapping that little icon would expand or collapse the account folder tree/list, while tapping the NAME part of the account-name would take you to the Inbox right away.
This is already how K-9 does it so it's nothing difficult or radical, the small difference being that K-9 shows the folder list in a popup window instead of simply expanding it downward, which Aquamail does and is preferable.
The unread counter is only visible when there are in fact, unread messages, so it is not always available to be used in this fashion. Many times upon entering the app I want to jump quickly into an account's Inbox even when there are no new unread items, just to review some old ones or reply to one I'd read previously but not yet responded.
I think that more often, a user will want to jump into his Inbox, rather than expand and view additional folders, so that should be the "main" function activated by tapping the account name. The less frequent function of expanding the folder tree, should be reserved for the smaller finger-touch area, the small icon at the far left representing a folder.
I can attach a screenshot from K-9 here to show exactly what I mean, but of course, K-9 is so well known that I'm sure this isn't necessary as its interface will be familiar. Also, I'm not suggesting to turn Aquamail into a K-9 copy, since I prefer the AM interface and functionality in almost every other way. This is just one small feature where I think K-9 does it in a more user-friendly way, that hopefully AM can incorporate somehow.
If you don't want to change the whole current behaviour what tapping the account name does, at the very least you could have the unread counter always visible, even when it's zero, so the user can still quick access the Inbox with one click on it at any time.
Thanks...
EDIT: Come to think of it, you would not really even need to create a new "folder icon" to place at the far left of the account name on the main list.. You could continue using the expand/collapse arrow that's already in place. Just have it be its own separate clickable zone, which performs a different action from clicking on the main account name.
