Applied when run update Spamassasin (or sa-update -D -v) get error
/etc/cron.daily/spamassassin:
error: unable to refresh mirrors file for channel updates.spamassassin.org, using old file
channel: could not find working mirror, channel failed
sa-update failed for unknown reasons


Try this:
 chown -R u:g /var/lib/spamassassin

chown -R debian-spamd:debian-spamd /var/lib/spamassassin