Summary
Setting up Sender Policy Framework (SPF) is a critical step for email deliverability and preventing spoofing. However, it can become a significant challenge when your Email Service Provider (ESP) does not offer clear or comprehensive documentation on how to configure your SPF record. This situation often leaves senders guessing or searching for external guidance, increasing the risk of misconfiguration that could lead to emails landing in spam folders or being blocklisted.
Key findings
- Documentation deficit: Many ESPs, particularly smaller ones or web hosting providers, lack explicit guides for SPF setup, often burying the information under generic 'sender authentication' settings without using the term SPF.
- Impact on searchability: The absence of specific SPF terminology in documentation makes it nearly impossible for users to find relevant setup instructions through searches.
- Indirect identification: Identifying the correct SPF includes or IP addresses often requires inspecting email headers or using DMARC reports to determine the actual sending sources, rather than relying on provided guidelines.
- Risk of misconfiguration: Without clear guidance, there's a higher chance of incorrect SPF records, leading to authentication failures and potential email deliverability issues. For more details on troubleshooting, see how to troubleshoot SPF authentication issues.
Key considerations
- Verify Return-Path: SPF checks the domain in the Return-Path (envelope-sender) header, not just the 'From' address. You need to identify the domain used by your ESP for this header.
- Use DMARC reports: If you have DMARC implemented, your aggregate reports (RUA) will show which IP addresses are sending mail on behalf of your domain and whether they pass SPF authentication. This is an excellent way to discover unlisted senders. For more information, read how to verify DMARC, DKIM, and SPF setup.
- Contact support: Even if documentation is sparse, reaching out to your ESP's technical support team directly can often yield the necessary SPF record includes or IP ranges.
- Examine common includes: Many web hosting providers or smaller ESPs use common include: mechanisms that are not widely publicized. Inspecting emails sent from the ESP might reveal these. A helpful resource for understanding SPF basics is the Mailgun SPF records guide.
What email marketers say
Email marketers often find themselves in a bind when trying to ensure proper SPF setup for their clients but are met with a lack of clear guidance from the Email Service Providers. This situation is particularly frustrating as it can directly impact campaign performance due to emails being marked as spam or blocked. The consensus is that ESPs should provide straightforward documentation, but when they don't, marketers must get creative.
Key opinions
- Documentation is key: Marketers strongly prefer ESPs that offer explicit, easy-to-find SPF setup instructions, as it streamlines client onboarding and ensures proper authentication.
- Vague terminology: Many ESPs use general terms like 'sender authentication' without mentioning SPF directly, making it difficult for marketers to search for or verify the correct settings.
- Challenges with multiple ESPs: The problem is compounded when a client uses multiple ESPs, each potentially having different or obscure SPF requirements. For guidance on this, refer to how to set up email authentication for multiple ESPs.
- Reliance on support: Without documentation, marketers often resort to contacting ESP support teams, which can be time-consuming and inefficient.
Key considerations
- Proactive inquiry: Before committing to an ESP, verify their SPF documentation availability. Ask specific questions about their SPF configuration process.
- Impact on deliverability: Incomplete SPF setup can lead to emails failing authentication, increasing spam rates, and potentially getting your domain on a blacklist or blocklist. Learn more about why your emails go to spam.
- Educate clients: Inform clients about the importance of SPF and why clear ESP documentation is vital for smooth email operations.
- Alternative methods: If documentation is unavailable, marketers may need to explore tools that help identify sending IPs or use DMARC reports. A good starting point for understanding SPF setup is the FluentSMTP guide on SPF.
Email marketer from Email Geeks explains they usually rely on ESP documentation to set up SPF for clients. They take the specific values provided by the ESP, add them, and then pass this information on to the client for implementation. This process is standard for ensuring proper email authentication.
Email marketer from Email Geeks notes that their client's current ESP provides no search results for SPF documentation. Although the ESP mentions a checkbox for 'sender authentication,' it fails to offer any specific details or values needed to actually publish an SPF record, creating a significant hurdle for proper setup.
What the experts say
Email deliverability experts agree that lacking clear SPF documentation from an ESP is a common but problematic scenario. They suggest that while ESPs should ideally provide this information, senders can use advanced techniques, like analyzing DMARC reports or inspecting email headers, to independently determine the necessary SPF entries. This proactive approach is vital for maintaining email deliverability and avoiding blocklists, even when direct guidance is absent.
Key opinions
- DMARC reports are essential: Experts strongly recommend leveraging DMARC aggregate reports to observe the outgoing email stream and identify the IPs being used by an ESP, which helps in constructing an accurate SPF record. Learn how SPF, DKIM, DMARC, and dedicated IPs affect deliverability.
- Web hosting specific challenges: Many web hosting providers (e.g., Bluehost, HostGator) have incorrect SPF setup processes via cPanel/WHM, often requiring undocumented includes that are difficult to find.
- Inspect email headers: Analyzing the full email headers of messages sent through the ESP can reveal the Return-Path domain and sending IP addresses needed for SPF. This can also help you understand the impact of the 'from' domain record on SPF.
- Direct ESP communication: If documentation is unavailable, experts advise directly asking the ESP for their SPF requirements or for a specific include to add to your DNS record.
Key considerations
- Proactive DMARC monitoring: Set up DMARC monitoring even if you don't have a strict policy. The reports will provide crucial data on your email streams, helping you verify SPF authentication for all senders.
- Avoid guesswork: Do not guess SPF records, as incorrect entries can lead to hard fails or soft fails, negatively impacting your sending reputation and increasing the chance of being blacklisted or blocklisted. Understanding security gaps with SPF can help.
- Leverage community knowledge: Sometimes, other users of the same ESP might have documented their SPF setup in forums or blogs, offering clues when official documentation is missing.
- Test thoroughly: After implementing any SPF changes (even inferred ones), use SPF validation tools and monitor deliverability closely to ensure emails are authenticated correctly.
Deliverability expert from Email Geeks offered to check their database for the ESP in question, suggesting that experts often maintain their own records of SPF settings for various providers due to inconsistent public documentation. This highlights a common expert strategy for dealing with absent or unclear ESP guidelines.
Email expert from SpamResource emphasizes that proper SPF configuration is crucial for avoiding spam folders, even if ESP documentation is lacking. They recommend monitoring mail logs and DMARC reports as reliable ways to identify the correct sending IPs for your domain.
What the documentation says
Official documentation, primarily the SPF RFCs (like RFC 7208), defines how Sender Policy Framework should function and be implemented. While these documents don't specifically address the absence of ESP documentation, they provide the foundational knowledge necessary to infer or verify SPF requirements. Understanding the core principles of SPF helps in troubleshooting situations where direct ESP guidance is missing.
Key findings
- SPF's primary purpose: SPF is designed to prevent sender address forgery by allowing a domain to publish a list of authorized mail servers that can send email on its behalf. Find out more about what the full form of SPF is.
- DNS TXT record: The SPF record must be published as a TXT record in the domain's DNS, starting with v=spf1.
- Mechanism usage: SPF records use various mechanisms (e.g., a, mx, ip4, include) to specify authorized hosts, with include being crucial for third-party ESPs. For more information, read how to format SPF TXT records.
- Return-Path domain: SPF validation occurs on the domain found in the Return-Path header (also known as the MailFrom or envelope-sender), which is often controlled by the ESP.
Key considerations
- The RFC is the ultimate source: When ESP documentation is missing, the official RFC 7208 (Sender Policy Framework) serves as the definitive guide to SPF syntax and mechanisms.
- DNS lookup limits: SPF records have a 10 DNS lookup limit, which includes any include mechanisms. Exceeding this limit leads to a permerror and can cause deliverability failures.
- SPF alignment: For SPF to align with DMARC, the domain in the Return-Path header must match the organizational domain in the 'From' header (or a subdomain thereof).
- Best practices: Always ensure your SPF record explicitly authorizes all legitimate sending sources to avoid emails being flagged as spam or getting your domain placed on an email blacklist (or blocklist).
RFC 7208 (Sender Policy Framework) states that SPF is designed to detect sender address forgery. It explains that a domain publishes an SPF record to specify which mail servers are authorized to send email on its behalf, thereby helping recipient servers verify the legitimacy of incoming mail.
The Internet Engineering Task Force (IETF) documentation on SPF emphasizes that the SPF record must be a TXT record in the DNS. It details the various mechanisms and qualifiers (e.g., 'a', 'mx', 'ip4', 'include', 'all') that can be used to define authorized senders and how they interact to determine SPF pass or fail.
