[IMP 2.2] In IMP's status bar, above the mailbox index or message body part of the display, "new" refers to messages which have not been read since they arrived, while "recent" refers to messages that have arrived since the last time you looked at the mailbox's index.
In mailbox view, IMP occasionally shows the recipient, instead of the sender, of the message.
IMP's mailbox view shows the recipient in the From column on messages for which you are the sender. (In other words, since you sent it, you know who the sender is, so IMP tells you who you sent it to.) This is particularly useful for the sent-mail and drafts folders