When comparing kmail vs Evolution, the Slant community recommends Evolution for most people. In the question“What are the best Linux email clients?” Evolution is ranked 3rd while kmail is ranked 11th.
Ranked in these QuestionsQuestion Ranking
Pro Proper kde intergation
Its the only graphical email client which is properly integrated into kde plasma.
Pro Has system tray icon
Good integration with plasma 5
Pro Supports POP3 and IMAP mailboxes
Pro Great integration with Gnome environment
Pro Manages contacts, tasks, calendar and memos as well
Pro Supports exchange servers
Evolution is one of the few Linux desktop e-mail clients that's supports exchange servers.
Pro Excellent GPG support
The integration with GPG is excellent. You can sign, encrypt, decrypt, authenticate and verify GPG signatures and GPG signed/encrypted email messages. All of that is just a setting away.
Pro HTML rendering is great
Of the many email clients available on GNU/Linux, Evolution has the best HTML renderer. It renders HTML and the entire email content exactly like it would appear on a full blown web browser. Not many email clients are capable of doing that.
Pro Clean interface with 2 layout variants
Going to View > Preview has the option of switching between "Classical View" and "Vertical View".
Pro Good support for Google's services
Con Buggy as of 2020
There are many bugs which are hard to track down in kmail, sometimes without any useful logs for troubleshooting. Sometimes the bugs are related to supportive applications like Akonadi, ect.
Con Buggy related kdepim applications
kmail by itself isn't the only application which is buggy, the many of the kdepim applications are buggy as of spring 2020.
Con Poor UX
The user experience of kmail is extremely poor comparison to Thunderbird or evolution on Linux.
Con No google support
You cant pass google 'Authentication' for the majority of the kdepim applications, The only support which works is via the kde 'online accounts' under 'system settings'. This only supports youtube and google hangouts integration.
Akonadi needs lot of ram
Con Limited configuration options
Cannot format date as preferred.
Con Poor integration in any non-GNOME desktop
It is written with GNOME in mind.
Con Can be wobbly with EWS
Don't be surprised if you have to reboot it a couple of times during a working day, because error messages are piling up (e.g. connection lost, can't sync, can't store appointment, read only). Then again, is this Evolution, or what it connects to? And since such an occasional reboot is dwarfed by the fact that MS365 seems to make full IMAP/ SMTP access (close to) impossible (nice meeting invite, THX, but when is it?), just reboot and get some work done...
Con No configuration messages
Although base functions like bullets, numbered, or pre-formatted text are possible, you can't select or set the font for your messages. Not even serif or sans serif. Which is a bit spartan TBH.
Con Can't choose different settings for each mail account
Settings have to applied to all mail accounts.
Con Only available on Linux
If you have to switch to another platform for whatever reason, you will need to search for a different email client.
Con RAM heavy
Very heavy on RAM usage.