> Self-hosting a good spam/phishing filter seems almost impossible in 2021 No, it's very easy to filter spam locally. You don't need huge amounts of data, just

> Self-hosting a good spam/phishing filter seems almost impossible in 2021 No, it's very easy to filter spam locally. You don't need huge amounts of data, just your regular email. Which makes it much better on your data. Running my own email infrastructure for a long time, filtering spam is a non-issue.