rspamd latest version not installable on Debian buster

I noticed I can not update rspamd on my Debian 10.13 buster host. It seems the latest rspamd just released days ago, requires packages that are not available in Debian 10. Perhaps someone follows rpamd development and knows what this is about?

Code:

root@posti:~# cat /etc/debian_version
10.13
root@posti:~# apt policy rspamd
rspamd:
  Asennettu: 3.4-1~buster
  Ehdokas:   3.5-1~0c671194e~buster
  Versiotaulukko:
     3.5-1~0c671194e~buster 500
        500 http://rspamd.com/apt-stable buster/main amd64 Packages
 *** 3.4-1~buster 100
        100 /var/lib/dpkg/status
     2.7-1~bpo10+1 100
        100 http://deb.debian.org/debian buster-backports/main amd64 Packages
     1.8.1-2+b2 500
        500 http://mirror.hetzner.de/debian/packages buster/main amd64 Packages
        500 http://deb.debian.org/debian buster/main amd64 Packages
root@posti:~#

Code:

root@posti:~# LANG=C apt install rspamd
Reading package lists... Done
Building dependency tree       
Reading state information... Done
Some packages could not be installed. This may mean that you have
requested an impossible situation or if you are using the unstable
distribution that some required packages have not yet been created
or been moved out of Incoming.
The following information may help to resolve the situation:

The following packages have unmet dependencies:
 rspamd : Depends: libc++1-16 (>= 1:16.0.0~++20230308013049+7b4e71bcf991) but it is not installable
          Depends: libc++abi1-16 (>= 1:16.0.0~++20230308013049+7b4e71bcf991) but it is not installable
          Depends: libunwind-16 (>= 1:16.0.0~++20230308013049+7b4e71bcf991) but it is not installable
E: Unable to correct problems, you have held broken packages.
root@posti:~#

Code:

root@posti:~# apt search libc++1-16
Sorting... Valmis
Full Text Search... Valmis
root@posti:~# apt search libc++abi1-16
Sorting... Valmis
Full Text Search... Valmis
root@posti:~# apt search libunwind-16
Sorting... Valmis
Full Text Search... Valmis
root@posti:~# 

Host has no packages in hold state.

 

I answer my own question:
Rspamd 3.5 released on 2023-03-20, the relase notes state:

So Debian 10 and Ubuntu 18.04 are not supported in Rspamd 3.5.
Rspamd reasons: https://rspamd.com/packages_support_policy.html
Rspamd updates and installs on Debian 11, I do wish rspamd would have supported Debian 10 for longer, but so it goes. Although Rspamd repository should not have rspamd 3.5 for buster when it can not be installed on buster.

 

I am on Debian Buster with ISPConfig 3.2.9 and amavis and want bullseye and rspamd.
Should i migrate to Spamd first (with this HowTo https://www.howtoforge.com/replacing-amavisd-with-rspamd-in-ispconfig/ ) or updating to bullseye first?
What order would you chose?
Yours, Gerd