Questions
What is DKIM?
DKIM adds a digital signature to every email you send. Receivers look up your public key in DNS and check the signature, which proves the message really came from your domain and wasn't changed on the way.
What is a DKIM selector?
A domain can have several DKIM keys, each under its own name called a selector, such as google or selector1. The key lives at selector._domainkey.yourdomain. Open an email from the domain, view the original message, and find s= in the DKIM-Signature header to see which selector it uses.
Why wasn't my key found?
Your provider probably uses a custom selector this tool doesn't guess, such as Amazon SES's random names. Enter the selector from a real email's DKIM-Signature header. If it still isn't found, the record may be missing or published under the wrong name.
Is a 1024-bit key OK?
It still works, but 2048-bit keys are recommended and are what Google, Microsoft and most providers create today. Keys under 1024 bits are ignored by Gmail.
More email tools
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- Check which SMTP ports are openTest all four mail ports of a server at once and see which answer, which are blocked, and what the server says when it picks up.
- MX lookupSee which mail servers receive email for a domain, in priority order, with their IP addresses and a quick health check.
- SPF and DMARC checkerCheck whether your domain's SPF and DMARC records are set up correctly, in plain language, so your email reaches the inbox and nobody can pretend to be you.
- Email blacklist checkCheck an IP address, or a domain with its mail servers and website, against Spamhaus, SpamCop, Barracuda and 13 other spam blocklists at once.
- Email warmup plannerPlan how fast to raise your sending volume on a new domain or mailbox, day by day, so Gmail and Outlook learn to trust you instead of sending you to spam.