Murray’s blog spurred some controversy about Evolution and the adapted Camel that Tinymail internally uses.
Having done most of the adjustments I’d like to point out that some of the changes are indeed focused on mobile use. Some of the changes alter the IMAP communication in such a way that less bandwidth is consumed. Examples are omitting the references header while downloading so-called summary information per message and the support for CONDSTORE.
CONDSTORE is a recent enhancement to the IMAP protocol that makes it possible to ask the IMAP servers for just the differences since a certain known state. Rather than asking for all the flags of an item, comparing that with your local version and synchronizing the two, you ask for only what has changed and you synchronize the recent local changes remotely.
I removed the support for the references header in Tinymail because this was poorly implemented in my opinion: a doubly linked list was used for each reference. This as you know consumes eight extra bytes per reference for the pointers (for the purists: on a 32bit computer). I think just storing the string and using strtok would be better here. The current E-mail clients being developed using Tinymail, however, don’t need the threading granularity of a desktop E-mail client.
Most modern E-mail clients are also less and less utilising this feature the way most experienced E-mail users know it: usually E-mails are grouped together based on relevance (flagging by a human and determining this with an algorithm) or on indeed the discussion thread. Full threading is often overkill: most people just want the messages to be grouped together somehow (in a flat list per group, not really the actual tree). Mind that most mobile devices have rather limited display capabilities and that a tree wastes a lot of whitespace this way. What is the use of message threading if you can only display at most five rows of E-mail summary info?
This “references information” must be downloaded and GPRS sometimes costs the end-user money per downloaded megabyte. Those reasons combined made me decide to simply not request this information. Later I might make the projection of the actual query definable by the application developer who builds on top of Tinymail.
My conclusion? Certain things can most likely be backported to Evolution. Other things might just not be interesting. Cooperating is definitely more interesting than not doing so. Right now is an internal highly adapted copy of Camel the pragmatic right solution for Tinymail.