To look at all the mailboxes on the server and see how many RECENT
mails there are. For the postfix-users list, I see that there are 6
recent messages. And if I do the list of mailboxes command again, it
returns the same count. Then if I go and look at the postfix-users
folder with my iphone, I see that I have 11 unseen messages. And
without opening a single message, I went back to my other MUA and
listed the folders, and now I have 0 unseen messages for 'postfix-users'
I'll have to see if I can log the commands sent by my iPhone from the
server side to see what's going on here. But as you can see, it's an
annoying behavior.