Don't know about rspamd, but SpamAssassin used to be way too aggressive in its stock config. E.g., it had a default rule for some "MS-Outlook" headers that just

Don't know about rspamd, but SpamAssassin used to be way too aggressive in its stock config. E.g., it had a default rule for some "MS-Outlook" headers that just happen to be in every email sent from Outlook via a non-Exchnage mail server. That created a ton of false positives - wasn't hard to fix, but still it was a hassle.