Introduction:
For a long time under Debian Wheezy Spamassassin was running quite well until I upgraded the system to Jessie. That is when Spamassassin(spamd) started to crash every now and then without giving much reasons why.

Cause of error message:
Looking in the system logs(/var/log/syslog) I found the following error:
spamd[7490]: util: refusing to untaint suspicious path: "/${SAHOME}"
I’m not sure if this is the cause of the crashes but it certainly doesn’t help. So I figured I should first try to solve this error first. According to this site since the Spamassassin is now started via ‘systemd’ the variables set in the init config file (/etc/default/spamassassin) are not expanded and they are passed on ‘as-is’ on the command line for starting spamd process. eg.
SAHOME="/var/lib/spamassassin/"
OPTIONS="--create-prefs --max-children 5 --username spamd --helper-home-dir ${SAHOME}"

Solution:
Since this file will not be overwritten during updates the suggestion was to write the value of this variable directly in the OPTIONS line in (/etc/default/spamassassin) as follows:
OPTIONS="--create-prefs --max-children 5 --username spamd --helper-home-dir /var/lib/spamassassin/"
Now at least this error doesn’t occur any more and time will tell if the crashes of spamd are still happening.