CertaDNS
Glossary

Mail transport

HELO / EHLO

The greeting a sending server opens an SMTP session with, naming itself. The name given is a claim and is not verified; EHLO is the extended form that also asks what the receiver supports.

Defined in RFC 5321 §4.1.1.1.

Where this appears

The lessons that use this term, and what each is for.

Email Authentication FundamentalsInside an SMTP conversationRead an SMTP transcript and identify each identity the sending server claims.Advanced Email TrustForward-confirmed reverse DNSVerify that a sending host names itself consistently in three places, and fix it when it does not.