[masklinn]

> Unfortunately it includes my biggest gripe about IMAP -- the requirement that messages are given a server-side message number. Maybe breaking with IMAP on this would make interop too hard though.

I don't understand this criticism, the criticism is usually that IMAP does not require maintaining UIDs (the server can announce UIDNOTSTICKY[0])

> While I'm on the subject, another less-common POP3 extension I liked was "XTND XMIT". This gave a simple way for the POP3 client to send mail

https://news.ycombinator.com/item?id=4826447

> IMAP has actually been extended to support that feature (not just kind of randomly, but by the IETF "Lemonade" working group), even allowing (in concert with other extensions) compositing a message from parts (such as attachments) on the server without having to download them first to the client.

> However, and I think this is actually more relevant in this context, Mark Crispin was an "opponent". (Note: the following e-mail snippet by Mark Crispin, was written years after the Lemonade Submit proposal expired, and thereby should be considered to already take into account that context.)

>> For many years, there have been various proposals to add mail sending capabilities to mail access protocols such as POP and IMAP.

>> These proposals are always strongly opposed. It is one of the "attractive nuisances" of email protocols. The value of the capability is obvious to many people, but the high cost of having it in POP or IMAP is much less obvious.

>> I am one of the opponents. For the past 25 or so years we have been in the overwhelming majority. It is quite unlikely that this concensus will change. If anything, it has become stronger in recent years.

>> […]

>> If you're not really that curious, suffice it to say that the people who design the protocols and systems understand the attraction but have excellent reasons not to do it.

http://mailman2.u.washington.edu/pipermail/imap-uw/2009-Janu...

[0] http://mailman2.u.washington.edu/pipermail/imap-protocol/200...

[brongondwana]

Mark Crispin was wrong. The underlying model of IMAP is strong, but a lot of the complexity of mail access comes from clients working around things which are either broken or missing in the protocol.

Their reasons aren't excellent, they are some theoretical notion of purity which leads to things like the "MOVE" capability taking years to finally happen, and everyone implementing copy+store+expunge independently and poorly in the meanwhile.

He's dead now, so he can't tell me I'm a feckless Gen X with no clue how to do real protocols - but there's a reason why proprietary protocols like ActiveSync get traction, and it's not because you need to pay a licence fee - it's because they actually solve problems that need solving.

[nmjenkins]

(Author of the spec here)

We will be adding sending to the JMAP spec, although support may be optional. The way it currently works at FastMail is a bit too specific to our architecture though, so we want to clean it up before adding it to the spec.

[masklinn]

>>> These proposals are always strongly opposed. It is one of the "attractive nuisances" of email protocols. The value of the capability is obvious to many people, but the high cost of having it in POP or IMAP is much less obvious.

[nmjenkins]

Lucky I'm not considering adding it to either POP or IMAP then. :)

[masklinn]

Good luck with your doom-repeating experiment, I guess.

[bodyfour]

> the criticism is usually that IMAP does not require maintaining UIDs

Yes, exactly. UIDs should be sticky, but they should also be allocatable by widely distributed nodes without the need for central coordination.

If your UIDs are 32-bit monotonically-increasing integers then this is impossible. If they are 128-bit random numbers you get it for free. If you prefix them with a timestamp you even get reasonable ordering.

The entire UIDNOTSTICKY problem is a result of IMAP UIDs being so restricted.

I can see why a proposal as complicated as Lemonade failed to get traction, but I find the argument pretty thin. The "attractive nuisance" was the old open-relay SMTP infrastructure. If you were writing a POP client in 1991 you wouldn't think twice about sending mail since you just had to hit a SMTP server (didn't even have to be the "right" one!) and the mail would get delivered. When this all came crashing down far more effort got put into authenticated SMTP (talk about not separating concerns!) than would have been required to just get message submission right in the first place.