How does changing DKIM selectors impact email reputation and what are the best practices for key rotation?

Email marketer from Mailhardener Blog suggests using multiple DKIM selectors to facilitate smooth key rotation. This involves setting up multiple selectors simultaneously, allowing for a seamless transition when rotating keys without impacting email delivery.

Marketer from Email Geeks advises clients against changing DKIM selectors unless there's a real operational need.

Email marketer from Reddit advises rotating DKIM keys at least annually, and more frequently if you suspect a compromise. Regular rotation minimizes the risk of long-term damage from a leaked private key.

Email marketer from MXToolbox notes that after rotating your DKIM key it is vital to test the new selector to make sure it is working correctly.

Email marketer from SuperUser mentions that in addition to rotating your DKIM keys, you need to keep the old key live for some time to avoid bounces. Also never reuse a key and do not share the same selector for multiple domains.

Email marketer from dmarcian comments that you should monitor your DMARC reports after key rotation to make sure that your emails are still being authenticated. It allows you to quickly resolve issues.

Email marketer from AuthSMTP explains that using a longer key length such as 2048 bit improves security and using a shorter 512 bit key is now deprecated as it is insecure.

Email marketer from Email Discussions forum explains that the DKIM selector itself doesn't usually directly impact your reputation, it's more about how you manage the keys associated with it. Poor key management can negatively affect your reputation.

Marketer from Email Geeks explains it's technically possible to rotate a DKIM key without changing the selector, but the DKIM record TXT value would need to be changed simultaneously and that some major providers were saying "we put reputation checks on everything we can put it on", so that would mean DKIM selector as well.

Marketer from Email Geeks explains that Google uses IP/selector/domain pairs to identify senders.

Email marketer from SparkPost advises that a good sending reputation takes time to build but only a second to lose. Maintain your sending reputation by always following best practises for DKIM.

Email marketer from Stackoverflow shares that changing your DKIM selector can impact your email reputation if not done correctly. You should ensure the new DKIM record is properly propagated before you start using it, and old selectors should be retired so they can't be used maliciously.

Marketer from Email Geeks states that while technically possible to rotate a DKIM key without changing the selector, it is not a viable solution in most scenarios and that some ESPs are moving to CNAME DKIM authentication, which pretty much solves the issue.

Expert from Email Geeks mentions it is not possible to rotate your DKIM key without changing selector without there being risk of email being lost unless you only mail infrequently and rotate the key when you are not mailing.

Expert from Email Geeks explains if you don't change the selector you're not rotating your DKIM keys, which leaves you open to security risks like disgruntled ex-employees sending spam authenticated by you or phishing.

Expert from Email Geeks suggests ping-ponging between two selectors as a compromise for key rotation.

Expert from Email Geeks clarifies that using CNAMEs for the selector is just a way of being able to change the selector.

Expert from Email Geeks mentions that one ISP used to use selector as part of their reputation tracking, although this is not the correct approach.

Expert from Spam Resource, John Levine, explains that DKIM key rotation is important, however it is also important not to reuse the same key with a selector multiple times as this can lead to reputation degradation.

Expert from Word to the Wise, Laura Atkins, shares insight that longer DKIM key lengths, such as 2048 bits, are more secure. Shorter keys become easier to crack as computing power increases.

Documentation from RFC 6376, the DKIM specification, explains that the selector is used to locate the correct public key for verification. Changing the selector requires updating the DNS record to point to the new key.

Documentation from Cloudflare highlights the importance of properly configuring your DNS records for DKIM, including the correct selector. Incorrectly configured records will cause authentication failures.

Documentation from Google Workspace Admin Help explains that regular DKIM key rotation strengthens security by limiting the time a compromised key can be used. They recommend rotating keys every three to six months and provide steps to generate new DKIM keys, update DNS records, and activate the new key.

Documentation from Microsoft Learn explains that DKIM key rotation is important for security. They provide guidance on how to rotate DKIM keys in Office 365, including generating a new key pair, updating the DNS records, and enabling DKIM signing with the new key.