[MlMt] IMAP keywords, misusage

[Bill Cole]

On 17 Jan 2019, at 6:36, Alain Israel wrote:

> I am using Mailmate on different computers, and as I work with an 
> Exchange server, the tags are not maintained from one computer to the 
> other. I was thinking of using one (just one) of the « generic » 
> IMAP keywords to specifically tag certain messages (messages for which 
> I haven’t received an answer yet, but the purpose of this tag is 
> irrelevant), and keep this info on my 2 computers. However I wanted to 
> avoid any IMAP keyword that would automatically tag zillions of mails, 
> but identify, if possible, one keyword that would be attached by the 
> user only.
>
> I thought  I had the choice between *MDNSent* (not quite sure what it 
> is normally used for),

MDN = Message Disposition Notification

With Exchange, MDNSent means that the server has sent a notification in 
response to a request (embedded in message headers or requested in SMTP) 
by the sender to receive such a notification. This is the mechanism by 
which users in a shared Exchange environment can know when their 
co-workers have read a message.

I'm not sure that Exchange will allow MDNSent to be set persistently by 
an IMAP client. It WILL set the flag if Exchange itself or a MAPI client 
(mostly that means Outlook) sends a MDN.

> *Important* (not sure this one actually exists),

It does not, with a normal IMAP server. That abomination is generally 
implemented by an immutable sender-set message header. However, Exchange 
MAY also implement it for IMAP clients as a flag, so it MAY work anyway. 
Check what MM says the "Raw Flags" are on a supposedly Important 
message.

> *NotJunk* and *Flagged* (although it may automatically tag all the 
> mails I have already flagged).
>
> Does it make any sense?

Roughly as much sense as using Exchange at all...

If "Flagged" persists between clients on an Exchange server, you have 
your one working IMAP keyword. "NotJunk" should be persistent but it may 
have side effects, although they should be benign. Neither SHOULD be 
modified arbitrarily by Exchange, but that assumes they are supported by 
Exchange and that Exchange behaves rationally, which are dubious 
assumptions.

Making this all more vague, "Exchange" is not one thing. Because major 
updates are not free, there is a wide range of versions in use and there 
are many configuration options. To know what actually will work in your 
Exchange environment, you must test it.


(CAVEAT: I don't manage any Exchange servers and haven't even been a 
user of one in years, so some of the above is drawn from imperfect 
traumatic memory.)