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Re: [spf-discuss] PermError: Too many DNS lookups at Microsoft.com

2006-05-06 11:17:41
  "v=spf1
   mx
   include:_spf-a.microsoft.com
   include:_spf-b.microsoft.com
   include:_spf-c.microsoft.com
   ~all"

Lookup #1 for mx produces + 3 includes:

  mail exchanger = maila.microsoft.com
  mail exchanger = mailb.microsoft.com
  mail exchanger = mailc.microsoft.com

This is 3 more lookups.

1 + 3 + 3

Sub total = 7

It looks as though you may be counting DNS lookups differently from how the RFC does. According to the RFC, the subtotal at this point would simply be 4.

    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.

The limit is on the mechanisms/modifiers themselves, not the actual DNS lookups. (I personally would have preferred to count the DNS lookups actually made for the sake of accuracy, but this is easier to verify when inspecting records manually.)

--Marc

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