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SMTP (1982) predates DNS (1985). Reverse DNS was added to SMTP servers as an anti-spam feature about 15 years after HELO was established. But to be honest, I'
by quesera 6y ago
SMTP (1982) predates DNS (1985).
Reverse DNS was added to SMTP servers as an anti-spam feature about 15 years after HELO was established.
But to be honest, I'm not sure HELO was ever really useful. In the very early years, it might have been appropriate to reject messages where the MAIL-FROM domain did not match the HELO domain. Not for long though.
- albertgoeswoof 6y agoThis is the crazy thing about email, it's ancient, 39 years old. I bet it'll still be around in 20 years from today.
- srean 6y agoAh! That was the missing information. Thanks, now it makes sense