SPF (Sender Policy Framework) is an email authentication protocol that prevents spammers from sending emails on behalf of your domain. It works by publishing a DNS TXT record that lists all IP addresses and mail servers authorized to send email from your domain.
How SPF Works
- You publish an SPF record in your domain's DNS (e.g.,
v=spf1 include:_spf.google.com ~all). - When a recipient's server receives an email from your domain, it checks the SPF record.
- If the sending server's IP matches the SPF record, the email passes.
- If it doesn't match, the email is flagged or rejected.
Why SPF Matters for Cold Email
SPF is one of three pillars of email authentication (alongside DKIM and DMARC). Without SPF, anyone can spoof your domain and send emails pretending to be you. This leads to domain blacklisting and catastrophic deliverability damage.
Common SPF Mistakes
- Too many DNS lookups: SPF has a 10-lookup limit. Adding too many
include:statements causes SPF to fail silently. - Using
+all: This allows any server to send as your domain. Always use~all(soft fail) or-all(hard fail). - Forgetting secondary sending services: If you use SmartLead, Instantly, or any third-party tool, their servers must be included in your SPF record.