apt-get install rpamd:amd64=1.6.4-1~xenial
Reading package lists... Done
Building dependency tree
Reading state information... Done
E: Unable to locate package rpamd:amd64
root@maia:/etc/rspamd/local.d# apt-cache policy rspamd
rspamd:
  Installed: 1.6.5-1~xenial
  Candidate: 1.6.5-1~xenial
  Version table:
 *** 1.6.5-1~xenial 500
        500 http://rspamd.com/apt-stable xenial/main amd64 Packages
        100 /var/lib/dpkg/status