Setup checklist#
- ☐ Inventory every service that sends mail as your domain: your ESP, CRM, helpdesk, billing system, and internal mail server.
- ☐ Collect each vendor's SPF include mechanism (for example include:_spf.google.com) from their documentation.
- ☐ Publish one TXT record at the root of the domain starting with v=spf1, listing each include, then ending with ~all (softfail) while testing.
- ☐ Verify with a lookup tool that the record resolves and stays under 10 DNS lookups and 255 characters per string.
- ☐ Move to -all once DMARC reports confirm all legitimate sources pass.
Audit checklist#
- ☐ Confirm you are not: exceeding the 10-lookup limit, which causes a permerror and effectively disables SPF.
- ☐ Confirm you are not: publishing two SPF records on one domain; receivers treat this as a permanent failure.
- ☐ Confirm you are not: forgetting that SPF checks the Return-Path (envelope sender), not the visible From address, so forwarded mail often fails.
- ☐ Confirm you are not: using +all or leaving ?all in production, which authorizes everyone.
Ongoing monitoring#
- ☐ Weekly: review provider dashboards (Postmaster Tools, SNDS) and bounce logs
- ☐ Monthly: re-run the setup verification after any vendor or DNS change
- ☐ Quarterly: full audit against this checklist
Frequently asked questions#
Does SPF alone stop spoofing?
No. SPF validates the envelope sender, which spoofers can set to their own domain while forging the visible From. DMARC closes that gap by requiring alignment.
What does ~all versus -all mean?
~all is softfail: receivers mark but usually accept. -all is hardfail: receivers may reject. Start with ~all, graduate to -all once DMARC data is clean.
How do I fix 'too many DNS lookups'?
Remove unused includes, replace includes with ip4/ip6 mechanisms where vendors publish static ranges, or use an SPF flattening service.