Well, I've recently ported a massive setup of SA rules and I've tried to add all functions that are supported by SA to rspamd. The only ones unsupported are pyzor/razor/dcc (all that is covered by fuzzy check: https://rspamd.com/doc/modules/fuzzy_check.html).
Both systems support statistics (rspamd uses 5-gramms hidden Markov model and SA uses naive bayes), they both support different backends for statistics (redis and sqlite for rspamd), per-user statistics, autolearning. Among network checks, they support URIBLs, RBLs, DMARC, DKIM, SPF. Obviously, both systems support regexp rules. However, I'm not an expert in SA features and might thus miss something...
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Well, I've recently ported a massive setup of SA rules and I've tried to add all functions that are supported by SA to rspamd. The only ones unsupported are pyzor/razor/dcc (all that is covered by fuzzy check: https://rspamd.com/doc/modules/fuzzy_check.html).
Both systems support statistics (rspamd uses 5-gramms hidden Markov model and SA uses naive bayes), they both support different backends for statistics (redis and sqlite for rspamd), per-user statistics, autolearning. Among network checks, they support URIBLs, RBLs, DMARC, DKIM, SPF. Obviously, both systems support regexp rules. However, I'm not an expert in SA features and might thus miss something...