SPF: too many DNS lookups

RFC 7208 caps an SPF evaluation at 10 DNS lookups. Past that, receivers return permerror and stop authenticating your mail entirely.

What causes it

• Accumulating providers over time — each include: costs one lookup plus everything its own record chains to.
• Expensive includes: some single providers cost 5 or more lookups on their own.
• a and mx mechanisms, which each cost a lookup even though they look free.

How to fix it

The count is recursive, so the fix is usually to remove one expensive include rather than several cheap ones. The generator below shows the running cost of every provider as you add it, so you can see which one is pushing you over before you publish.

Check your domain

Also searched for: spf 10 lookup limit, spf lookup limit exceeded, more than 10 dns lookups.