The reality is that all desktop email clients suck and suffer from neglect. Mostly because hard-core people are using things like mutt or emacs for mail and everybody else is using webmail.
The reality is that IMAP effectively failed as a standard. The idea of 'mail folders' is somewhat of a improvement over the mbox format, but there was never any sort of search features or mail filtering features that became standardized for IMAP servers. There are a few aborted attempts and ways to program mail filtering, of course, but nothing that really works well or isn't confusing as hell for normal people.
Webmail effectively started off as browser-based IMAP clients, but they have progressed far far beyond that and solved most of the issues with syncing email to desktops, laptops, and phones.
Probably the answer to fixing this issue is going back to simple POP protocol and then using something like Notmuch to use 'search-like' features to logically group email into folders and such things without destructively editing emails like IMAP does. By this I mean with IMAP and maildir you are editing and moving files around on a remote file system and this means that if something goes wrong the mail gets duplicated or corrupted or out of order or whatever. By using a database-type approach with notmuch you are not touching the original emails for the most part, but simply editing and modifying metadata. The original structure and such are preserved.
Search is built into the IMAP protocol. [1]
Filtering doesn't belong at the IMAP protocol layer anymore than it belongs at the SMTP layer. That said, "Sieve" is really powerful, and there are many SMTP and IMAP servers which support it.
> Filtering doesn't belong at the IMAP protocol layer anymore than it belongs at the SMTP layer.
Right, so users are forced to set up this stuff for each and every device they have. This is a big reason why the exodus to webmail and the proprietary internal-only protocols they use.
Seive is really powerful and I've used it plenty of times, but it's not standard and is something that needs to be done completely separate from almost all email clients. Unless you are a big email nerd that runs your own servers it's pretty much worthless.
You can get desktop and web based and command line clients which talk the ManageSieve protocol so provide you with an interface to manage your server based sieve mail filters [1]
I'll agree that it's not common. Not because there is anything wrong with it, but because companies like Google decided to roll their own for whatever reason.
I can see use cases for needing to search across multiple folders. I guess I've not felt the need to do that myself before. However, no reason your IMAP client couldn't search folders one after the other, or open multiple connections and search multiple folders simultaneously.
It is, actually. https://wiki.tools.ietf.org/html/rfc5804
> something that needs to be done completely separate from almost all email clients.
In that it is not part of IMAP, yes. However, webmail clients like Roundcube and desktop clients like Thunderbird and Claws/Sylpheed all offer plugins.
When you choose the gnome flavor of said distros, I suppose that it comes with evolution because it is the official default email client for gnome until its replacement, geary, is ready. But last time I checked in 2015 it was still in early stages of development despite having started circa 2012.
So yeah, its a bit buggy, but it works for me
Then you can use any client you want.