Re: IMAP extensions needed for SPAM/HAM and WHITE/BLACK listing

[Cyrus Daboo <cyrus@xxxxxxxxxx>]

Hi Ned,

--On July 7, 2009 7:22:42 AM -0700 Ned Freed <ned.freed@xxxxxxxxxxx> wrote:

> Now suppose I implement this with folder annotations. I'm in business
> immediately. Things just work no matter what client people use.

Actually you need to consider what the user experience is likely to be on 
the client side. There are several things to consider: for spam messages 
users will typically want to delete them from their regular mailbox. With 
ham messages they will typically want to leave the message in place (or 
file them away after processing). In each case I certainly would not want 
the spam messages or an extra copy of the ham messages to reside on my 
server consuming quota or other resources, or being indexed as part of a 
server-wide search etc.

With that in mind lets look at how each solution might work client-side:

1) Keywords: for a spam message the user sets the spam keyword, then sets 
the deleted flag (and then may explicitly expunge if the client has that as 
an option as opposed to hide-deleted-messages with lazy expunge). For a ham 
message the user just sets the ham keyword. i.e. two user operations for 
spam, one for ham.

2) Mailbox (I am going to assume that the client has both a move and copy 
command available - the former implicitly setting the delete flag after the 
IMAP COPY command): for a spam message the user moves the message to the 
spam mailbox. For a ham message the user copies the message to the ham 
mailbox. NB both of these assume that the server does not actually store 
the spam/ham messages in the spam/ham mailboxes (or perhaps it garbage 
collects them).

Things to note: typically clients don't offer shortcuts "move to mailbox X" 
or "copy to mailbox X" so the mailbox operations will involve some drag and 
drop or menu list selection operation. The same may be true for setting 
arbitrary keywords (though Mail.app and I suspect Thunderbird do have 
buttons for this). Frankly the best user experience would be for the client 
to have spam/ham buttons and commands that would allow the user to do the 
appropriate actions in one click or keyboard shortcut operation - that is 
certainly important if the level of spam is moderate to high.

So at the end of the day, for the best (and frankly simplest) user 
experience clients do have to change for both the keyword and move to 
mailbox approaches. Now for keywords that change does have to be immediate 
if arbitrary keyword support is not already present in the client, whereas 
for move to mailbox, or clients already supporting keywords, that change 
can be done over time - though as Ned points out client changes tend to 
happen on geological time-scales!

So other approaches to consider:

1) An extension with commands SPAM and HAM to explicitly tag one or more 
messages.
2) A "forward to spam/ham" option that specifies special email addresses 
for the user where spam/ham can be forwarded to trigger training.
3) An IMAP URL handed off to the SPAM system with URLAUTH to allow that to 
pull details of the message for training. (This could be tied to (2) in 
that forward-without-download could be used in (2) with URLAUTH etc).

These of course all require new client/server behaviors and thus are 
probably non-starters, but they should not be dismissed entirely.

--
Cyrus Daboo