What SPF does
SPF (Sender Policy Framework) is a TXT record that lists the servers allowed to send email for your domain. Receivers compare the sending server with your list. Without SPF, anyone can send mail that claims to be from you, and your own mail is more likely to be filtered.
The 10-lookup limit
Every include:, a, mx, exists and redirect in SPF costs a DNS lookup, and so does every one inside the records you include. More than 10 in total and SPF fails for every message (a permerror). This checker follows every include and counts them for you, so you can see which service is using up the budget.
Common SPF mistakes
- Two SPF records. Adding a second v=spf1 record for a new service breaks both. Merge them into one.
- Ending with +all or ?all. +all allows everyone; ?all gives no guidance. Use ~all or -all.
- Forgotten services. Includes for tools you stopped using still cost lookups.
- Using ptr. It is deprecated and slow.
A typical record for Google Workspace plus a website contact form on cPanel looks like v=spf1 include:_spf.google.com a mx ~all.