A LOT of those e-mails are still being delivered to inboxes created over a year ago. Of course, it's against my users privacy to actually look at them, but just by taking a look through some of the subjects it's easy to see they are spam.
QuickInbox for the free gift.
The stats page counts ALL incoming e-mail. It does not differ between e-mails going to active inboxes and e-mails that are not going to an active inbox. So yes, most of it is considered spam. They are e-mails that the user is no longer interested in receiving.
Another thing to consider is if you create an inbox today and make it expire in a month, if you go back to it on a daily basis those would not be considered new inbox creations, so the user is actually checking the e-mails received.
I keep track of read e-mails, but that statistic is not public
What do you guys think of the stats graph?