I like mail notifications on kanboard and in order to be able to use threading in my client mail, it will be nice to add “In-Reply-To” header to mail notifications.
Values defined in this header could be in this form : <Kanboard-BASE_URL-ID_TASK> so threading should be good even with multiple kanboard instance.
header_checs.pcre (to be completed according to the different topics generated by the kanban) :
/^Subject: .=?utf-8?Q?([0-9]+)?=$/ PREPEND In-Reply-To: kanban-udl-$1
/^Subject: .=C2=B0([0-9]+)/ PREPEND In-Reply-To: kanban-udl-$1
And yes, In-Reply-To works well with Thunderbird but not with Zimbra web client for example.
I have tested only with References header surrounding by <>, it’s works with the two clients + Gmail.