How do I properly set up SPF and DKIM records for email marketing, including handling multiple SPF records, IP ranges, bounce capturing, and Google Postmaster Tools verification?
Summary
What email marketers say10Marketer opinions
Email marketer from Stack Overflow clarifies that the correct SPF syntax involves using 'include:' mechanisms to reference other domains' SPF records and that using 'ip4:' and 'ip6:' mechanisms should be limited to only the IP addresses that you directly control.
Email marketer from Sendinblue explains that DKIM adds a digital signature to your emails, verifying that the email was sent by the authorized domain and that the message content hasn't been altered during transit, thereby improving email deliverability.
Email marketer from SparkPost shares that properly handling bounces (both hard and soft bounces) is crucial for maintaining a good sender reputation. Implementing a feedback loop and removing invalid email addresses from your list are essential.
Marketer from Email Geeks explains the correct syntax for combining SPF records, advising against separate `v=spf1` entries and suggesting a merged format. He also questions the use of a /18 IP range for email.
Marketer from Email Geeks advises creating a separate TXT record for the `google-site-verification` value and retrying verification in Google Postmaster Tools if the domain isn't visible there yet.
Email marketer from Quora suggests implementing DMARC (Domain-based Message Authentication, Reporting & Conformance) in addition to SPF and DKIM to provide instructions to receiving mail servers on how to handle emails that fail SPF and DKIM checks, enhancing overall email security.
Email marketer from Litmus stresses the importance of consistent monitoring of your email authentication setup and deliverability metrics to quickly identify and address any issues that may arise due to changes in your sending infrastructure or email practices.
Email marketer from Mailjet shares that setting up an SPF record involves creating a TXT record in your domain's DNS settings that specifies which mail servers are authorized to send emails on behalf of your domain.
Email marketer from EmailGeeks Forum discusses the concept of 'SPF flattening,' which involves resolving all 'include:' statements in your SPF record to a list of IP addresses to avoid exceeding the DNS lookup limit and improve authentication speed.
Email marketer from Reddit advises that having multiple SPF records can cause authentication failures. The recommendation is to consolidate all authorized sending sources into a single SPF record.
What the experts say4Expert opinions
Expert from Email Geeks asks if the domain is used in the 5321.from address and whether bounces are correctly captured and sent back to NGP. Suggests that if not, an SPF record including NGP values may not be necessary for that domain.
Expert from Email Geeks advises against listing an entire colo space in the SPF record due to potential forging risks and recommends listing only directly assigned IPs. Mentions the potential of poor delivery at Gmail because of this type of error.
Expert from Word to the Wise explains that DMARC provides benefits to all mailbox providers, but those benefits are only realized if the sending side properly implements DMARC. Implementing DMARC ensures that receivers understand how a sender treats messages that fail authentication. You want to start with 'p=none' to observe.
Expert from SpamResource explains that common SPF mistakes include having multiple SPF records, failing to update the SPF record when sending infrastructure changes, and exceeding the DNS lookup limit. Also, make sure all sending sources are defined within the SPF record, to avoid failures.
What the documentation says6Technical articles
Documentation from Google Workspace Admin Help explains that Sender Policy Framework (SPF) is an email authentication method designed to detect forging sender addresses during the delivery of email. SPF allows receiving mail servers to check that a message claiming to come from a specific domain is submitted by an IP address authorized by that domain's administrators.
Documentation from RFC 6376 specifies the DomainKeys Identified Mail (DKIM) Signatures standard, outlining the technical details of how DKIM signatures are generated, verified, and used to authenticate email messages.
Documentation from Microsoft Learn explains how to set up SPF records to authenticate outbound email from your Microsoft 365 domain. The documentation emphasizes the importance of having only one SPF record for your domain.
Documentation from RFC 4408 provides the technical specification for the Sender Policy Framework (SPF) for Authorizing Use of Domains in E-Mail, detailing the syntax, semantics, and implementation considerations for SPF records.
Documentation from Postmark explains that Google Postmaster Tools provides valuable insights into your email sending reputation, spam rate, and other deliverability metrics, helping you identify and address any issues affecting your email performance with Gmail users.
Documentation from DKIM.org explains that DomainKeys Identified Mail (DKIM) is an email authentication system designed to verify the DNS domain of an email sender and the integrity of the message. It uses cryptographic authentication.