On 13 Nov 2002 at 14:25, Mark Crispin wrote:
> > What is the proper action to take when a client issues a SUBSCRIBE
> > command with a parameter that already appears in the subscription list?
> > Should a duplicate be created, or should the existing entry be removed
> > from the subscription list?
>
> The IMAP protocol takes no position on whether or not duplicate entries are
> permitted in the subscription list. I don't think that it should.
>
> There is a wide range of behaviors in IMAP that are permitted (by
> virtue of not being explicitly prohibited), but are "silly" for one
> reason or another. Duplicate subscription seems to me to be such a
> "silly" behavior; it is generally avoidable, and can not be reliably
> used to accomplish anything.
For your interest... I asked this question because I have a situation with
my IMAP server at present; the Endymion "Sake" webmail server
routinely issues a SUBSCRIBE command every time it selects a folder -
according to the author of the product, he does that to satisfy the needs
of a specific, very large legacy customer.
Mercury *allows* duplicate subscriptions - specifically, according to a
comment I've made in the source... I don't remember the incident, but it
seems that there was a particular client that was using the subscription
list to store preference settings, not folder names, and that it would
occasionally duplicate some entries. For the life of me, I can't remember
what the client was.
I don't have any particular position on this - I'll happily modify Mercury's
handling of SUBSCRIBE to match the most common behaviour - I
guess the issue is just what that might be...
Opinions?
Cheers!
-- David --
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