A security researcher is currently warning of a problem with Siri.
Under macOS Siri creates a database in which diverse user information is collected. Including emails. The problem, according to security expert Bob Gendler, is that these messages are stored there in plain text.
Disabling Siri does not help
Even more problematic, according to Gendler: Even if Siri is deactivated, according to Gendler's observations would still continue to store unencrypted e-mails. In the email app itself, all messages are encrypted and could not be read so easily.
Manually deactivate learning from email
According to the security researcher, attackers can easily read critical information from their email traffic via the unencrypted database.
Good to know: You can disable this by disabling the reading of emails in the Siri settings.