Gmail – Display the size of each email/conversation in Gmail

Yes you can do this but not without a little bit of hacking around.

From my answer at Equivalent of 'archive' for priority inbox \ multiple inbox :

The only way that I have found to do it is either with the element inspector in chrome/safari or with firebug in firefox. The good news is that once you have made the settings change it will work in all browsers.

1. Go to the priority inbox settings tab.
2. Click the options next to the section you want to show your work mail.
3. Click "More Options..."
4. Inspect the element for the "Work" Label
5. You will notice on the surrounding div there is an attribute cfg="^all,Work", change the value to "^i,Work"
6. Select the label on the page as you normally would

You will know if it worked or not straight away because the section settings should now read : Inbox, Work instead of the All Work that it used to read.

Here is a list of alternative commands you can use. You can chain commands together with a comma.

^i = Inbox
^u = Unread
^io_im = Important
^t = starred
^f = sent
^r = drafts
^all = All mail (include archive)

ie. ^i,^u,Work = all emails in your inbox, that are unread with the label "Work".

Obviously there are no rules about this, but a sensible way to use Gmail features would be:

• Leave email in the inbox if it still requires action (some kind of reply or action on your part)
• Archive email once it no longer requires action on your part
• Use the star to flag important messages
• Use labels to categorize messages
• Delete messages you will not need in the future

In this way, the inbox is thought of as your to-do list. Anything in your inbox is something you need to deal with. "Dealing with it" could be replying, researching for more information about something, categorizing for later reference, etc. As you go through your messages, you deal with them then archive them once you've taken the necessary action.

If you need to find an old message you've already "dealt with", you can either search for it (the preferred way), or you can look through the starred messages or through your labels.

Labels and stars are for categorization. The "inbox" label performs the same function as a physical inbox sitting on your desk: It's a list of things you need to do. You don't store things in your inbox, you deal with them then route them wherever they need to go.