What are the best practices and considerations for using SPF record redirects?
Summary
What email marketers say12Marketer opinions
Email marketer from EasyDMARC shares that SPF redirects, using the 'redirect=' mechanism, allow a domain to delegate its SPF record to another domain. This is useful when multiple domains use the same mail servers. However, EasyDMARC recommends being cautious as excessive redirects can cause SPF validation to fail due to DNS lookup limits. They advise monitoring SPF authentication results after implementing redirects.
Email marketer from Sendinblue highlights that both SPF and DKIM are crucial for email authentication and deliverability. They recommend implementing both SPF and DKIM, and monitoring their performance regularly. SPF records should be checked for accuracy and compliance with best practices, including avoiding excessive includes and redirects.
Email marketer from Email Geeks explains that the reason for using a redirect (or include) in an SPF record instead of listing all the IPs is likely due to the administrator wanting to maintain only one record instead of two for easier management, regardless of how frequently the list changes.
Email marketer from Mailhardener states that setting up SPF correctly from the beginning can save a lot of deliverability headaches in the future. They recommend to start simple, validate and test the SPF records, and only add complexity (such as includes and redirects) when absolutely necessary. Always consider the potential impact on DNS lookup limits.
Email marketer from dmarcian reiterates the importance of understanding the 10 DNS lookup limit in SPF, including lookups caused by redirects. They suggest regularly auditing SPF records to remove unnecessary includes and redirects, optimizing the records to stay within the lookup limit. This helps prevent SPF failures and improves email deliverability.
Email marketer from EmailOnAcid notes that chaining multiple SPF redirects can quickly exhaust the DNS lookup limit, leading to SPF failures. They recommend minimizing the use of redirects and instead consolidating IP addresses and domains into a single SPF record whenever possible. They also suggest using SPF record testing tools to identify potential issues.
Email marketer from MXToolbox explains that SPF redirects should only point to domains that you control and that have correctly configured SPF records. Redirecting to third-party domains you don't control can pose a security risk and may lead to authentication failures if their SPF records are misconfigured.
Email marketer from Email Geeks shares a negative aspect of using SPF redirects is that it counts towards the SPF DNS lookup count.
Email marketer from Reddit shares that while SPF redirects are convenient, they can introduce complexity and potential issues with DNS lookup limits. He suggests carefully planning and testing SPF records with redirects to avoid deliverability problems. It's also a good idea to regularly review the SPF records of redirected domains to ensure they remain valid.
Email marketer from Stackoverflow notes that SPF redirects can simplify SPF record management when multiple domains share the same sending infrastructure. However, it is critical to ensure that the redirected domain has a valid and up-to-date SPF record. Failure to do so can result in SPF failures and negatively impact email deliverability.
Email marketer from Postmark explains that understanding SPF is essential for good email deliverability. SPF records, especially with redirects, need to be carefully configured and monitored. If an SPF record is not set up correctly, ISPs may flag your emails as spam or reject them outright. Always validate changes and monitor your deliverability.
Email marketer from AuthSMTP explains that while both 'include' and 'redirect' are used in SPF records, 'include' is generally preferred for incorporating other domains' SPF records. 'Redirect' should be used when the entire SPF record is delegated to another domain, which is less common. They recommend using 'include' for most cases where external domains need to be authorized.
What the experts say4Expert opinions
Expert from Email Geeks explains that SPF record redirects allow the referenced domain to manage IPs for outbound mail without using a CNAME, which can interfere with other records on the domain.
Expert from Word to the Wise explains that SPF redirects are indeed counted toward the total DNS lookup count limit of 10. This needs to be carefully considered as part of any SPF record deployment.
Expert from Email Geeks explains that using 'redirect' in an SPF record is a more appropriate and flexible approach than using a CNAME. There is no negative or positive impact in this particular case.
Expert from Email Geeks clarifies that 'redirect' isn’t exactly the same as 'include' or 'CNAME'. It affects the SPF resolver's internal state, changing the implied domain to the redirect's target. Its error handling differs from 'include', and unlike 'CNAME', it counts towards the ten DNS query limit.
What the documentation says4Technical articles
Documentation from Microsoft highlights the 10 DNS lookup limit within an SPF record evaluation. Redirects count towards this limit. If the evaluation exceeds 10 DNS lookups, SPF will return a 'PermError' which might cause email deliverability issues. Careful management of SPF records, especially with redirects, is crucial.
Documentation from RFC 7208 specifies that the 'redirect' mechanism causes SPF evaluation to restart using the SPF record of the domain specified in the redirect. The result of the evaluation of the redirected domain becomes the result of the current SPF evaluation. It notes that redirects count towards the DNS lookup limit and can impact performance if overused or chained excessively.
Documentation from OpenSPF details the correct syntax for using the 'redirect' mechanism in SPF records. It highlights that the redirect mechanism should point to a valid domain and that the domain should have a valid SPF record. OpenSPF recommends thorough testing and validation of SPF records to ensure proper functionality.
Documentation from Google Workspace Admin Help explains that using the 'redirect' mechanism in SPF records is supported but advises caution. It functions by delegating SPF evaluation to another domain. If the target domain's SPF record passes, the original domain also passes SPF. Misconfiguration can lead to authentication failures. It is recommended to ensure that the target domain has a correctly configured SPF record.