What are common misconceptions and best practices regarding SPF records and email deliverability for small mail servers?
Summary
What email marketers say10Marketer opinions
Email marketer from MXToolbox shares the best practice of using tools like MXToolbox to validate your SPF record syntax and ensure it doesn't contain errors that could impact deliverability.
Email marketer from EmailOnAcid advises including all third-party senders (e.g., marketing automation platforms, transactional email services) in your SPF record to ensure their emails are authenticated.
Email marketer from Mailjet shares the technique of SPF flattening to avoid hitting the DNS lookup limit, improving email deliverability for small mail servers.
Email marketer from Postmark recommends using a hard fail (`-all`) at the end of your SPF record to instruct receiving servers to reject emails that don't match your SPF policy, improving deliverability and security.
Email marketer from SparkPost emphasizes the importance of regularly monitoring your SPF records and authentication results to identify and fix deliverability issues quickly.
Email marketer from Reddit mentions the misconception that `?all` or `~all` are always safe. He warns over permissive records can be exploited by spammers and damage your sender reputation.
Email marketer from Superuser explains not to have multiple SPF records. It leads to errors and unpredictable behavior. Combine all mechanisms into a single SPF record.
Email marketer from GMass highlights SPF changes can take time to propagate across the DNS system. Always test your SPF record, but allow for DNS propagation time when making any changes to avoid errors.
Email marketer from Stack Overflow highlights the need to understand the `include` mechanism in SPF and the potential for recursive lookups exceeding the limit. He suggests to keep SPF records simple.
Email marketer from EasyDMARC shares that common SPF errors include having too many DNS lookups, using incorrect syntax, and failing to include all sending sources. These errors can negatively impact email deliverability.
What the experts say7Expert opinions
Expert from Email Geeks shares her experience with a small mail server, noting that Gmail didn't put their mail into bulk, even after moving the server and not publishing -all. She uses this as a counterexample to claims of Gmail being evil.
Expert from Email Geeks shares his perspective on SPF, stating, "I don't believe in SPF in the way I don't believe in parking tickets, not in the way I don't believe in bigfoot."
Expert from Spamresource.com explains that common SPF mistakes include exceeding the 10 DNS lookup limit, not including all sending sources, and using incorrect syntax.
Expert from Email Geeks explains that mail from previously unknown IPs is often considered spam by default, requiring senders to prove otherwise.
Expert from Wordtothewise.com answers explains one of the biggest and most common problems with SPF records occurs when people forward mail. She shares you may need to rewrite the envelope sender, so SPF will pass.
Expert from Email Geeks points out the danger of using useless SPF records. She highlights a recommended SPF record is downright stupid and broken.
Expert from Wordtothewise.com shares that `exists` is a DNS mechanism that requires the querying server to resolve a domain and verify that an A record, AAAA record, or CNAME record exists. This is slow and often not helpful.
What the documentation says4Technical articles
Documentation from DMARC.org clarifies that for DMARC to pass based on SPF, the domain in the `Mail From` address (Return-Path) must align with the domain used in the SPF record. This is a common misconception that affects DMARC compliance.
Documentation from Google Workspace Admin Help explains that SPF records have a lookup limit of 10, which can cause issues if exceeded, impacting deliverability. Exceeding the limit can cause SPF checks to fail.
Documentation from Microsoft Learn advises that for Exchange Online, you need to include the SPF record that specifies Microsoft's servers to ensure proper email authentication and deliverability.
Documentation from RFC 4408 defines the Sender Policy Framework (SPF) specification, which is crucial for understanding how SPF works and its limitations regarding DNS lookups and syntax.