[MlMt] Hijacking field for "Due Date"

[Bill Cole]

On 17 Nov 2016, at 15:18, Zvi Biener wrote:

> Hi Folks,
> I'd like to be able to associate a due date with email messages. 
> Currently, I can do this through tags, but if there are multiple tags 
> already associated with a message, it makes sorting difficult. Is 
> there an imap field I can perhaps hijack in order to do this? The 
> field can be local only - synching with the server would be nice, but 
> not essential.

Short answer: There's no way for MailMate to do that.

The only attributes of a message that IMAP allows to be changed are 
message flags (which MM's Tags are mapped to) and which mailbox the 
message is in. The only way to modify anything else about a message 
(like a header) would be to delete the original message and store a new 
one. While MM obviously has a client-side copy of all messages, it 
doesn't offer any way to change messages locally except by changing 
aspects that represent IMAP flags: both those mapped to user-defined 
tags and those with distinct well-defined meanings like \Seen, $Junk, 
\Deleted, etc.

However, you could mimic an arbitrary field by "hijacking" the "Source 
Mailbox" field. Create folders on the IMAP server named by date and move 
messages with due dates into them. Then you could create a smart mailbox 
that includes all messages from all of the dated folders, and use the 
"Source Mailbox" field for sorting.

I do a similar thing with mailing list mail. I have an IMAP mailbox for 
each list I subscribe to, all inside a no-messages parent mailbox named 
"Lists." I rarely open those mailboxes, but instead have a smart mailbox 
searching all messages from that IMAP account with "Lists" in the source 
path newer than one week.