And just out of curiosity:
The reason why kde-standard, kdepim etc. depending on kmail won't budge is a strange dependency.
kmail wants ($ dpkg -s kmail):
Depends: ..., libkf5akonadisearchdebug5-22.12, ..., libkf5akonadisearchpim5-22.12, ...
and the old packages libkf5akonadisearchdebug5_22.12.3-1+b1_amd64.deb and libkf5akonadisearchpim5_22.12.3-1+b1_amd64.deb
provide ($ dpkg -I libkf5akonadisearchdebug5_22.12.3-1+b1_amd64.deb, $ dpkg -l libkf5akonadisearchpim5_22.12.3-1+b1_amd64.deb):
Provides: libkf5akonadisearchdebug5-22.12,
Provides: libkf5akonadisearchpim5-22.12
as their only provisions.
The new replacements libkf5akonadisearchdebug5t64 and libkf5akonadisearchpim5t64 on the contrary provide
($ dpkg -s libkf5akonadisearchdebug5t64, $ dpkg -s libkf5akonadisearchpim5t64):
Provides: libkf5akonadisearchdebug5 (= 4:22.12.3-1.1), libkf5akonadisearchdebug5t64-22.12
Provides: libkf5akonadisearchpim5 (= 4:22.12.3-1.1), libkf5akonadisearchpim5t64-22.12
Although they provide the t64-22.12 versions, they fail to satisfy kmail's ...5-22.12 requirements.
I think this is a miss. Until kmail (or the replacements) fix the miss here is a quick solution:
Change to the tmp directory:
$ cd /tmp
Create a temporary sub directory:
$ mkdir kmail
Get kmail:
$ apt-get download kmail
Extract kmail:
$ dpkg-deb -x kmail_4%3a22.12.3-1_amd64.deb kmail
extract the control file to kmail//Debian:
$ dpkg-deb --control kmail_4%3a22.12.3-1_amd64.deb kmail/DEBIAN
Use your favorite editor and change the control file together with the version information:
$ vi kmail/DEBIAN/control
4:22.12.3-1 -> 4:22.12.3-1b
libkf5akonadisearchdebug5t64-22.12 -> libkf5akonadisearchdebug5-22.12 | libkf5akonadisearchdebug5t64-22.12
libkf5akonadisearchpim5t64-22.12 -> libkf5akonadisearchpim5-22.12 | libkf5akonadisearchpim5t64-22.12
Repack kmail::
$ dpkg -b kmail kmail_4%3a22.12.3-1b_amd64.deb
Clean up the mess:
$ rm -rf kmail kmail_4%3a22.12.3-1_amd64.deb
Install the modified version of kmail::
$ sudo dpkg -i kmail_4%3a22.12.3-1b_amd64.deb
Now the dist-upgrade should proceed without errors regarding kmail, kde-standard, kpim and co.
Enjoy!