DKIM selector names by provider
A DKIM public key is published at selector._domainkey.yourdomain.com. Each sending service picks its own selector. To check or monitor DKIM you need to know it. This list covers the defaults; several providers let you choose a custom selector during setup, in which case use the one you chose.
| Provider | Default selector(s) | Record type |
|---|---|---|
| Google Workspace | google | TXT, 2048-bit recommended |
| Microsoft 365 / Exchange Online | selector1, selector2 | CNAME to selector1-yourdomain-com._domainkey.yourtenant.onmicrosoft.com |
| Mailchimp | k1, k2, k3 | CNAME to dkim.mcsv.net |
| SendGrid | s1, s2 (also smtpapi, em) | CNAME |
| HubSpot | hs1, hs2 | CNAME |
| Zendesk | zendesk1, zendesk2 | CNAME |
| Mandrill / Mailchimp Transactional | mandrill (also mte1, mte2) | TXT / CNAME |
| Postmark | pm or a numeric selector like 20240101pm | TXT |
| Amazon SES | Three random selectors (Easy DKIM) or ses/custom (BYODKIM) | CNAME |
| Mailgun | mailo, k1, smtp | TXT |
| Zoho Mail | zmail or numeric | TXT |
| Proton Mail | protonmail, protonmail2, protonmail3 | CNAME |
| Fastmail | fm1, fm2, fm3 | CNAME |
| Klaviyo | kl, kl2 | CNAME |
| Brevo (Sendinblue) | mail | TXT |
| Mimecast | mimecast20190301 or custom | TXT |
Find the selector for a specific message by opening its headers and reading the s= tag in the DKIM-Signature line.
Check a selector now
Run a check and add ?selectors=name1,name2 to the report URL, or add selectors to a monitored domain so they are verified every day and you are alerted when one disappears.