Assertion: email | /r/HasProperty | smtp
Facets:
Source sentences:
text: Some popular methods for filtering and refusing spam include email filtering based on the content of the email, DNS-based blackhole lists (DNSBL), greylisting, spamtraps, enforcing technical requirements of email (SMTP), checksumming systems to detect bulk email, and by putting some sort of cost on the sender via a proof-of-work system or a micropayment.
text: The main protocol that is used when sending e-mail -- SMTP -- does not include a way to authenticate .