What is SPF (Sender Policy Framework)?
SPF works through DNS records where domain owners publish a list of authorized sending IP addresses or mail servers. When receiving mail servers get email claiming to be from a domain, they check whether the sending server’s IP is listed in that domain’s SPF record. If the IP matches the published policy, the email passes SPF; if not, it fails. SPF helps prevent domain spoofing by making it verifiable whether email actually originated from authorized infrastructure. However, SPF has limitations including not validating the “From” header users see (only the envelope sender), breaking during email forwarding, and providing no protection against lookalike domains. SPF is most effective when combined with DKIM and DMARC as part of comprehensive email authentication.
Business Impact
Implementing SPF improves email deliverability by demonstrating your messages are legitimate and reduces the ability of attackers to spoof your exact domain. However, SPF alone doesn’t prevent most phishing since attackers can use lookalike domains with valid SPF records or exploit SPF’s technical limitations. Organizations must maintain SPF records as their email infrastructure changes, ensuring all legitimate sending sources are included while avoiding exceeding SPF’s lookup limits. Overly restrictive SPF policies can block legitimate mail; overly permissive ones provide little security value.
Allure Security's Approach
While SPF protects your legitimate domains, comprehensive email security requires monitoring for lookalike domains used to bypass SPF, spoofed emails exploiting SPF limitations, and analysis of the broader threat landscape beyond what SPF addresses.