I know this behavior, but I did not know the reason.
In such cases or freshly installed systems I train my system manually.
- Download spam samples from http://untroubled.org/spam/:
wget http://untroubled.org/spam/2021-01.7z - unzip:
7za x 2021-01.7z - train:
rspamc learn_spam 2021/01/* - check:
[root@srv01 ~]# rspamc stat
Total learns: 1055
Sincerely, Marko