While send-hook, fcc-hook, and fcc-save-hook allow printf-like sequences in the filename parameter, mbox-hook does not allow it in the mailbox parameter, so this patch was created to address that.
If you intend to use this patch, please check your existing mbox-hook commands for the use of percent chars ('%'). If you want a literal percent char in your mailbox name, then it must be quoted; use "\%" or "%%" in its place.
I generally use this for my mailing list mailboxes, which I prefer to have stored by date. For example:
subscribe mutt-users@mutt.org mailboxes +lists.d/mutt/users/incoming fcc-save-hook '~C mutt-users@mutt.org$' +lists.d/mutt/users/%<%Y/%b> mbox-hook '+lists.d/mutt/users/incoming' +lists.d/mutt/users/%[%Y/%b]
2008-09-26: Patch updated for 1.5.18.
2004-02-13: Patch updated for 1.4.2.
2004-02-02: Patch updated for 1.5.6.
2003-11-27: Patch updated for 1.5.5.
2003-03-20: Patch updated for 1.5.4 and 1.4.1.
2003-01-25: Format change for 1.4i patch.
2003-01-17: Patch updated for 1.5.3.
2002-12-07: Patch updated for 1.5.2.
2002-08-31: Patch updated for 1.5.1.
2002-08-25: Patch updated for 1.4i.
2002-03-13: Patch updated for 1.3.27
and 1.3.28.