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DKIM selector

Also known as: selector, DKIM key name

A DKIM selector is a short label that points to one specific signing key in your domain settings — it lets each mail service have its own key, so checks land on the right one.

What it is

DKIM works by signing your email with a key, and publishing the matching key in your domain settings so receivers can verify it. The selector is the short label that names which key to use. A domain can have several keys at once — one for your normal email provider, another for your newsletter tool, another for your invoicing app — and the selector tells the receiver which one to look up for that particular message.

You’ll see selectors as short names in DNS, like selector1, google, or s1. Each mail service tells you which selector to set up; you rarely choose it yourself.

Why it matters to your business

Mostly this is plumbing you don’t need to think about — but it matters in two practical ways. First, if a selector is set up wrong or points to a missing key, DKIM silently fails for that service, weakening your email’s trustworthiness and hurting deliverability. Second, when you add a new tool that sends email in your name, it usually needs its own selector and key added — otherwise that tool’s mail isn’t properly authenticated and is more likely to hit spam.

So when you bring on a new sending service, “set up its DKIM selector” is the step that keeps your email landing in the inbox.

How to tell / what to do

Our free checker flags whether your DKIM is set up correctly. If a service’s mail is failing authentication, the fix is to add or correct its selector and key — a configuration step done by whoever manages your email, following the provider’s instructions. It’s free. See the DKIM fix guide.

Want to fix this on your own domain? See the free guide →