A number of reviews mostly not all that recent have pointed to the main clients as Thunderbird, Evolution, Claws-mail, and Kmail as possibilities. Up to about a year ago Thunderbird seemed to be
"the" email client with the best mix of positives.
However there are no recent reviews that I have seen and in the meantime Thunderbird has moved to monthly releases which are more maintenance releases, with security fixes, with little real functional change — and little new development. Thunderbird won't be changed into the future much, if one interprets the available news information.
Evolution is reported to be rather prone to being buggy, and kmail even more so. Claws-mail has limitations as does kmail.
So where is the future going without any real innovation on available linux mail clients? We need a well maintained and capable mail
client, with preferably good calendar integration (webcal/google calendar), properly supported html composing, good maildir format storage for local mail, good security support including the capacity
to deal with both gpg and s/mime encryption and signing. It needs a good modern UI, and good import/export facilities as well as good
integration with its address book, including good import/export of addresses.
Are we likely to see this kind of package as we move into the future or will mail clients slowly disappear?
At the moment it looks like email client support is dead — maybe users are moving more into web mail and the cloud rather than having a properly functional mail client on their desktops?
I wonder what do people think?"