Email / MX
MX, SPF, DMARC and common DKIM selectors.
Email setup for croweb.host
MX records
| Priority | Server | TTL |
|---|---|---|
| 5 | mail.croweb.host | 38400s |
SPF
v=spf1 a mx a:croweb.host ip4:80.80.49.100 -all
DMARC
v=DMARC1; p=reject; pct=100; ruf=mailto:postmaster@croweb.host; rua=mailto:postmaster@croweb.host
DKIM
no common selectors found
About Email / MX
This tool checks the four DNS records that determine whether your outbound email reaches the inbox: MX for routing incoming mail, SPF for declaring which IPs may send on your behalf, DMARC for setting your authentication policy, and DKIM for cryptographically signing messages. It probes nine common DKIM selectors automatically (google, default, selector1, selector2, mail, k1, dkim, s1, s2) so most setups light up without manual selector entry.
When to use it
Run this before sending a marketing campaign to verify deliverability fundamentals are in place. Check it after migrating to a new mail provider, since the new MX and SPF need time to take over from the old. Use it as the first diagnostic when a recipient reports your mail landing in spam, since missing or weak SPF and DMARC are the most common root causes.
How to read the results
A green pass on all four records means the basics are configured. SPF should include or ip4 your sending servers and end with -all or ~all rather than +all. DMARC starts with v=DMARC1 and includes a policy of none, quarantine, or reject. DKIM only needs one valid selector returning a public key, and the selector your sender uses depends on which mail platform you run.
Frequently asked questions
What is the difference between SPF and DKIM? ▾
SPF lists which IP addresses may send mail for your domain. DKIM adds a cryptographic signature to each outgoing message, which receivers verify against a public key in DNS. SPF protects the envelope, DKIM protects the message content.
My DMARC says p=none. Is that bad? ▾
p=none is a monitoring mode, not enforcement. Receivers report failures back to you but still deliver the mail. It is a fine starting point while you gather reports. Move to quarantine, then reject once you confirm legitimate sources are passing.
Why does the tool not find my DKIM selector? ▾
The tool probes nine common selector names. Custom selectors set by smaller providers will not be auto-detected. Check your sender's documentation for the selector name and verify it manually with a DNS query for selector._domainkey.yourdomain.
Do I need all four records? ▾
MX is required to receive mail. SPF, DKIM, and DMARC are all strongly recommended for outbound mail. Without them, legitimate mail is increasingly likely to be filtered as spam, especially by large providers like Gmail and Outlook.