What this check looks at
When a server opens an SMTP conversation it identifies itself with an EHLO (or HELO) command and a hostname. JoltMx validates the name your server presented:
- That a hostname was presented at all (RFC 5321 requires one).
- That it's a fully-qualified domain name, not an address literal like
[203.0.113.5]or a bare name likelocalhost. - That the name resolves in DNS - and ideally to the connecting IP.
Why it matters
The EHLO name is cheap for filters to cross-check and a reliable bot tell. Missing names, IP literals, and unqualified names like localhost are classic misconfiguration and spam signals. A clean, resolvable EHLO that matches your reverse DNS is exactly what receivers want to see.
How the diagnostic grades it
| Result | Severity | What it means |
|---|---|---|
| EHLO hostname resolves | Pass | A fully-qualified name that resolves (and ideally matches the connecting IP). |
| No EHLO hostname | Warning | The server presented none - treated as a bot signal. |
| Uses an address literal | Warning | An IP, not a hostname. Legal but heavily penalised. |
| Not fully qualified | Warning | A bare name like localhost - a misconfiguration signal. |
| Does not resolve | Warning | The name has no A record. Use one that resolves to your sending IP. |
How to fix it
- Configure your mail server to
EHLOwith its real fully-qualified hostname (e.g.mail.yourdomain.com). - Make sure that name resolves to your sending IP, and that the IP's PTR record matches it.