IMAP’s biggest problem is poor server implementations and big vendors who are not really supportive towards each other being the ones defining it. Not because they are the only ones at IETF who are vocal about the protocol. It’s because if the big players don’t implement the new enhancements, it basically boils down to not being used and the E-mail clients not adopting it. Quite funny is the fact that all those big players have their own closed protocols for E-mail too. That all those big players seem to consider their IMAP support to be of secondary priority.
If a new feature would make IMAP really a lot better than the closed solutions, then it does happen that the big vendors will especially not implement it. I suspect that’s because that would pose a direct risk for their own offerings.
Take a look at GMail’s CAPABILITY line if you think that Google is the God of good, the great and the brave. Their IMAP server is probably one of the poorest imaginable. You would think that Google would want to make a name for itself by introducing a really good IMAP server? Given that they hired thousands really excellent software developers and even at least one of the people who have been really closely involved in the creation of the IMAP standard, you would expect that. No?
Well, no. For Google it’s only the words “IMAP” and “support” that really matter. Just to get the sound of those two words in the minds of the people, and then that’s it. Nonetheless for IMAP’s name-reputation it’s actually good that Google did this. Google’s IMAP server doesn’t really show what a modern IMAP server would be capable of.
To show this, it lacks capabilities like COMPRESS and/or do compression over TLS. It lacks capabilities like CONDSTORE, QRESYNC and BINARY. It will probably not adopt anything the Lemonade group is doing at this moment, like CONVERT and NOTIFY. It also doesn’t do TLS correctly: it only supports wrapped mode for SSL. Making it hard for E-mail client developers to standardize on data encryption. And what about THREAD, SORT, UIDPLUS?
Probably because otherwise people would make fun of Google’s IMAP team, it looks like they did make it support IDLE.
Not very surprisingly are they offering mobile E-mail solutions that use their secret closed protocol. So much for Google being the most cool company humans ever created. In a way, they are doing exactly the same as Microsoft once did with embrace and extend. But in a more subtile way. In such a way that people keep believing: but hey, Google is cool! Summer of code! yeej! They do IMAP! And XMPP! Open formats! Open protocols!
Well, Microsoft does IMAP too. Their IMAP support in Exchange is actually better than Google’s IMAP server. It’s hard to be worse than Microsoft’s support for open protocols, but to get away with it for free? Just like any other IMAP server implementer has Microsoft got some of their things wrong. They usually actually do fix this. We’ll see how Google will play their IMAP game. I’m for sure going to be critical, no matter what.