SPF Fail: too many DNS lookups

I’ve had a couple folks come to me recently for help troubleshooting SPF failures. The error messages said the SPF record was invalid, but by all checks it was valid.
Eventually, we tracked the issue down to how many include files were in the SPF record.
The SPF specification specifically limits the number of lookups that can happen during a SPF check.

SPF implementations MUST limit the number of mechanisms and modifiers that do DNS lookups to at most 10 per SPF check, including any lookups caused by the use of the “include” mechanism or the “redirect” modifier. If this number is exceeded during a check, a PermError MUST be returned. The “include”, “a”, “mx”, “ptr”, and “exists” mechanisms as well as the “redirect” modifier do count against this limit. The “all”, “ip4”, and “ip6” mechanisms do not require DNS lookups and therefore do not count against this limit. Processing limits

Some senders are using include: records that then have include: records that then have yet other include: records. Looking up all these include records caused the SPF lookup limits to be reached, thus causing the SPF lookups to fail (all the records can’t be pulled). Note, a lot of SPF checks don’t actually comply with the SPF spec in this area. Because of the spotty compliance, some too long SPF records won’t fail everywhere.
How can you fix this?

  • Prune unnecessary :include files from the SPF record.
  • Use different domains for mail from different places so you don’t need one SPF record to rule them all.
  • Don’t publish SPF records, rely on DKIM for authentication. Even Hotmail is checking DKIM these days.

If you need to find out how many lookups your SPF record entails you can use the SPF checker at Enter in a domain in the box and hit go. Then click on the “DNS” tab to see the actual DNS lookups that are happening. Each red domain is a separate DNS lookup. has a lot of include: files and a lot of lookups. Because this is a checking tool, it doesn’t limit the number of queries (because that wouldn’t be useful). But in places that are implementing the spec correctly, and are refusing mail based on SPF failures, would experience mail failures.


  1. steve says

    The RFC mandated limit is actually the number of entries in an SPF record that trigger a DNS lookup rather than the number of DNS lookups caused. They’re pretty similar, as each include, a, mx entry in the original SPF record or any included records will cause a DNS lookup. But the A and AAAA lookups required to expand an MX entry don’t (as I read the RFC) count against the limit.
    You’re relying on the implementation the receiver is using reading that limit the same way I do, though, which isn’t a given. Generally it’s better to just use ip4, ip6 and (where needed) include records and avoid a and mx entries, anyway.

  2. henry says

    You can send an email to, it will check your spf and it verifies the lookup limit as well.

  3. Al Iverson says

    I demand one dollar in royalty for being the inspiration for this blog post!

  4. Steevo says

    Hm. I just checked two domains I work on and both have exactly 10 red lines.
    Somehow I think that doesn’t mean things are hunky dory.
    Not exactly sure what it does mean.
    I’d like to read some more about SPF. I read a lot but I really don’t exactly understand it very well.

  5. steve says

    Sounds like they’re fine, Steevo. explains the details of SPF. I’m not sure if there’s a decent less deep coverage of it – probably not, as SPF is all about the fiddly details.

  6. Steevo says

    As a test I did them both differently, but they both seem to work.
    They are both on dsl lines, and are both smarthosted through my ISP.
    On one SPF record I put in the ISP server, on one I did not.
    The test I did last night shows this correctly.
    As I said they both work. I can’t see why that is.
    I wish I knew how to put DKIM on that. I am sure no programmer.
    BTW, I still use Sam Spade Personal. Shows you how darned old I am.

  7. Rhet says

    I am curious on the recommendation of only relying on DKIM.
    How will that hold up if I want to use DMARC? Wouldn’t I be in a position where I have a single point of failure for my legitimate mail?

  8. sharif says

    I am receiving the below error..i can see only 7 red lines, pls advice how can i fix this..
    Results – PermError SPF Permanent Error: Void lookup limit of 2 exceeded
    my spf record
    v=spf1 mx ptr ip4: ip4: -all

    1. laura says

      I need to see the real SPF record to be able to provide any help with your issue.

  9. sharif says

    Hi Laura,
    Thanks for your help in this post.
    domain name –
    SPF checkup done –
    Error received- Results – PermError SPF Permanent Error: Void lookup limit of 2 exceeded
    As so far my SPF record was working without any issue and suddenly by today i have this error and it is something new which i ever see in any article, i will appreciate you quick reply on this subject. Thanks..

  10. laura says

    Where is the error message from? Is it possible this is simply a transient DNS error?

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  12. Russ says

    I receive this message:
    PermError SPF Permanent Error: Too many DNS lookups
    I ran that spf check you mention, and there were about 30 red domains listed on the DNS tab.
    What do I do?
    Any help appreciated.

  13. steve says

    Russ: You’ll want to reduce the number of queries required, using the techniques suggested in this post. Without seeing the records I can’t be more specific.

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  15. Alan Doherty says

    anyone needing help with spf record sanity just subscribe to spf-help
    and ask us to diagnose/fix yours
    and some simple rules
    ptr (never ever sane to use)
    mx (never ever sane to use)
    a (unless followed by :somename, is always a sign of sloppy admin)
    if your spf commits any of the above it can and should be improved/fixed/tuned up

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  17. Bobby says

    We use to fix this issue. You move your existing TXT record to and then replace your existing TXT for with: “v=spf1 include:%{l}._l.%{i}._i.%{h}._h.%{d} ~all”
    It’s using a little known feature described in the SPF RFC to make this work.

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  23. Gangcai says

    If you are having the issue of exceeding the 10-DNS-lookup limit, you can try our Safe SPF feature, which is purpose-built to solve this very issue.

    Find out more at:


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