SPF Record Flattening Tool
Audit how many DNS lookups your SPF record triggers. If it exceeds 10, receiving mailboxes will return a fatal PermError. Our engine recursively expands your includes into clean, deduplicated IP ranges.
What is the 10 DNS Lookup Limit in SPF?
RFC 7208 Section 4.6.4 dictates that during an SPF verification, an MTA (like Gmail, Yahoo, or Outlook) must not perform more than 10 DNS queries across include, a, mx, ptr, and redirect mechanisms. This limitation was introduced in the late 1990s to prevent Denial of Service (DoS) amplification attacks against DNS root servers.
Today, when modern businesses configure Google Workspace (3 lookups), SendGrid (4 lookups), Zendesk (3 lookups), and HubSpot (3 lookups), they quickly reach 13 lookups. When an email exceeds 10 lookups, Gmail and Yahoo return spf=permerror, causing immediate DMARC failure and sending your messages to spam.
100% Pass Rate
Flattened records replace dynamic domain queries with raw CIDR ranges, bringing lookups down to 1 or 2 queries total.
Overcoming Vendor IP Drift
Third-party SaaS vendors frequently update their IP pools. Our Delivery Center Plus SaaS auto-syncs flattened records every 15 minutes.
Automatic Sub-record Splitting
If the flattened IP list exceeds 255 characters, our generator cleanly splits the record across _spf1 and _spf2 sub-records.
Want Automated 15-Minute SPF Auto-Sync?
Never worry about manual DNS updates when Google or Mailchimp adds new IPs. Delivery Center Plus automatically manages your flattened records in the cloud.