Can I have multiple DKIM keys?
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Yes, you can have as many DKIM keys as you need published simultaneously. Each key uses a different selector, so there's no conflict. When a receiving server checks your DKIM signature, the signature itself tells the server which selector to look up. Multiple selectors can coexist in your DNS without interfering with each other.
And there are a few common reasons to have multiple keys:
Multiple sending services. If you're using two different ESPs, or an ESP plus a transactional email service like Postmark, each service typically signs with its own private key and needs its own selector published in your DNS. You'll have separate records at something like mailchimp._domainkey.yourdomain.com and pm._domainkey.yourdomain.com.
Key rotation. When you rotate a DKIM key, you publish the new key under a new selector while the old one is still active. Once you've confirmed the new key is being used and working, you remove the old selector from DNS. This overlap period means you briefly have two valid keys, which is intentional.
Testing environments. If you run staging or development environments that send email, they often have separate DKIM keys from production. That way you can track which environment sent what.
But There's no practical limit to how many DKIM selectors you can have. Unlike SPF, which has a hard 10-lookup limit, DKIM doesn't impose count limits on published keys. The only real concern is keeping track of which selectors you've published and removing ones that are no longer in use. An old selector for an ESP you stopped using doesn't cause harm exactly, but it's clean practice to remove it.
Check all your current DKIM selectors with our free DKIM checker, or see how often to rotate DKIM keys for guidance on key lifecycle management.
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