This page collects ideas about a new mail detection/handling overhaul.
New mail handling/reporting
There seem to be the following major workflows we want to support:
- a folder with new mail has new mail if and only if it hasn't been opened/closed by mutt since last new mail delivery
- a folder with new mail always has the new mail flag regardless if opened or not
From discussion it seems people use different ways to remind themselves of things to be still looked at.
The idea behind the first approach is that once the user has visited the mailbox, they know whether they want to deal with the unseen mail. If they leave the mailbox with messages still unseen, they don't want to be told about it again unless it has received new mail since that time. Telling the user that there is new mail in the mailbox when it is actually just unseen makes it impossible for the user to tell whether really new mail has actually arrived.
For the latter, a mailbox-to-be-processed is one with a new mail flag. Otherwise flagging or marking messages as old identify mail to be defered for now because it makes the new mail flag for the mailbox disappear. Due to being flagged/marked as old they can later still be identified as to those needing to be looked at.
There's a nice old summary of the difference between mbox, maildir, and IMAP in mutt-dev <20060529120134.GA23719@cube.chello.upc.cz>. See this thread for discussion as of mutt 1.5.20.
It doesn't make any sense to have mutt announce that there's new mail in a mailbox you've just left. But it can make sense for it to appear in the buffy list.
Starting with 1.5.20 we do the latter for mbox as well as maildir (but not IMAP). However, many mbox users seem to miss the old behaviour and consider the new one an outright bug. This is exactly the opposite for maildir/mh users.
We could let $mark_old affect polling behavior: when set, mutt will not only mark unseen messages as old when leaving the mailbox, but it will also skip mailboxes that have only old messages in the list of mailboxes with new mail. Users that use $mark_old are most likely to want this behavior, as it is probably why they are using the old flag in the first place. However, it may be that there are people who do not want an Old flag on their messages but do want to skip mailboxes that mutt has already visited. This would require a separate flag, perhaps $show_unseen which would show mailboxes with unseen messages as well as new messages.
An option should be added that toggles between both; not sure about a default value as one group or the other will get changed behaviour by default. Inspecting $mbox_type sounds wrong.
For mbox/mmdf, the change would trivial, simply avoid looking for a new message in mbox_reset_atime().
For maildir, it could be implemented by changing the buffy check to report new mail only if we have a message with a mtime greater than the last check time in new/. The drawback is that this has the potential to slow things down depending on how many messages we have in new/ and many "seen" messages we need to skip (usually the first hit using readdir() reveals a non-trashed one so we can abort). Or we can use the mtime of new/ subdirectory if that's reliable enough (i.e. don't start looking if it's <= last time checked).
Appending new mail
New mail handling is different is when appending a new message to a folder from within mutt: For mbox/mmdf it doesn't raise the new mail flag, for maildir/mh it does.
This is not trivially solved as the mbox/mmdf driver doesn't care about what the other code appends to the folder (possible some copy routine). But it would need to inspect it in order to tell whether the there's at least one new message for the new mail flag. The easiest way was if we had an append method that passes the required info from HEADER down to mx driver. Right now, appending to mbox is cheap as we simply seek to the end and return the FILE pointer for appending (i.e. the mbox code itself doesn't know whether the message is new or not). Maybe we need something like mbox_commit_message() as other driver have (which would have the benefit of a cleaner mx API).
This is likely to trigger some complaints by users, too, I think because it changes well-known behavior for mbox.
This is consistent with the fix in [7d7976cd4fc4]: as FCC messages are known to the author, they're aren't new and thus shouldn't raise the new mail flag. However, there's at least one report in <20090701212335.GA3857@cefeid.wcss.wroc.pl> requesting the old behavior for mbox/mmdf. See ticket #1896.
There's a request in ticket #3295 to not mark postponed mail as new. This probably only matters when the user configures mutt to watch the postponed folder (watching it may make sense with an IMAP account that has a draft folder the user is subscribed to). One argument for marking postponed mail as read is that the message isn't actually unread but well known to the user.
All this should be solved for 1.6.
For people who keep new messages in their mailboxes (thus, having $mark_old unset), `set check_mbox_size=yes' might be a working workaround to bring back the old behavior.