"SPF Permanent Error: Too many DNS lookups" is a very specific problem. Your record is too big and SPF checkers will refuse to perform enough DNS queries to determine if something passed SPF.
The SPF spec allows at most 10 DNS lookups. Your SPF record has 17.
RFC 4408 § 10.1 – Processing Limits states:
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.
The "exp" modifier does not count against this limit because the DNS
lookup to fetch the explanation string occurs after the SPF record
has been evaluated.
Your SPF record has four lookups before traversing the inclusions, including your a
and mx
:
v=spf1 a mx ip4:162.123.189.010 include:_spf.google.com include:bluehost.com ~all
Google's SPF
Google has three DNS lookups for three collections of CIDRs that it blesses:
_spf.google.com (+3 lookups)
v=spf1 include:_netblocks.google.com include:_netblocks2.google.com
include:_netblocks3.google.com ~all
_netblocks.google.com
v=spf1 ip4:35.190.247.0/24 ip4:64.233.160.0/19
ip4:66.102.0.0/20 ip4:66.249.80.0/20 ip4:72.14.192.0/18 ip4:74.125.0.0/16
ip4:108.177.8.0/21 ip4:173.194.0.0/16 ip4:209.85.128.0/17
ip4:216.58.192.0/19 ip4:216.239.32.0/19 ~all
_netblocks2.google.com
v=spf1 ip6:2001:4860:4000::/36
ip6:2404:6800:4000::/36 ip6:2607:f8b0:4000::/36 ip6:2800:3f0:4000::/36
ip6:2a00:1450:4000::/36 ip6:2c0f:fb50:4000::/36 ~all
_netblocks3.google.com
v=spf1 ip4:172.217.0.0/19 ip4:172.217.32.0/20
ip4:172.217.128.0/19 ip4:172.217.160.0/20 ip4:172.217.192.0/19
ip4:108.177.96.0/19 ip4:35.191.0.0/16 ip4:130.211.0.0/22 ~all"
Bluehost's SPF
The SPF record for bluehost.com
is too large (its SPF record fails Google's MX tester on its own):
bluehost.com (5 lookups before further traversal)
v=spf1 include:spf2.bluehost.com include:_spf.qualtrics.com
include:_spf.google.com include:_spf.salesforce.com
include:sparkpostmail.com -all
spf2.bluehost.com (+0)
v=spf1 ip4:66.147.240.0/20 ip4:69.89.16.0/20 ip4:74.220.192.0/19
ip4:67.222.32.0/19 ip4:70.40.192.0/19 ip4:67.20.64.0/18 ip4:173.254.0.0/17
ip4:50.87.0.0/16 ip4:69.195.64.0/18 -all
_spf.qualtrics.com (+0)
v=spf1 ip4:139.60.152.0/22 ip4:162.247.216.0/22 ip4:54.186.193.102/32
ip4:52.222.73.120/32 ip4:52.222.73.83/32 ip4:52.222.62.51/32
ip4:52.222.75.85/32 ?all
(see above for _spf.google.com's +3 lookups, though redundant lookups don't add to your total)
_spf.salesforce.com (+1 using an SPF macro with the IP address)
v=spf1 exists:%{i}._spf.mta.salesforce.com -all
sparkpostmail.com is a redirection and then another exists
macro and a pile of pointers (+6, wow)
v=spf1 redirect=_spf.sparkpostmail.com
v=spf1 exists:%{i}._spf.sparkpostmail.com include:_netblocks.sparkpostmail.com
ptr:sparkpostmail.com ptr:spmta.com ptr:flyingenvelope.com ~all
Danger! That sparkpost.com inclusion pulls in some ptr
entries, which are arguably insecure, using a deprecated and "strongly discouraged" SPF mechanism (that's a direct quote from the spec).
_netblocks.sparkpostmail.com was pulled in by the previous record (+0)
v=spf1 ip4:147.253.208.0/20 ip4:192.174.80.0/20 ~all
Bluehost used to use SendGrid, who actually knows what they're doing (their SPF record has no additional lookups), but apparently they have traded SendGrid for SparkPost, who (based on their six extra lookups plus the insecure ptr
entries) does not.
Since that totals 12 (13 with include:bluehost.com
), you cannot include Bluehhost's SPF.
Bluehost's own suggested SPF record (and its default for all customers) is similarly broken (with 16 lookups, including an easily forged ptr
).
Solution for Bluehost: a trimmed and safer SPF record
Hello, Bluehost. I tweeted this at you. This section is just for you.
Bluehost could fix this with the following SPF records in place of their current one:
bluehost.com (7)
v=spf1 a include:spf2.bluehost.com include:_spf.google.com
include:_netblocks.sparkpostmail.com ~all
Though note that I had to downgrade include:sparkpostmail.com
(7 + 6 = 13, too large, plus that includes the dangerous ptr
records) to just its netblocks (7 + 0 ≤ 10). Bluehost needs to yell at SparkPost or go back to SendGrid. spf2.bluehost.com
is unchanged from its current state and should be the only inclusion necessary for Bluehost customers.
(I'd use the IP for the A
record to skip a lookup, but it changes so often that it looks like fast flux.)
Bluehost should suggest customers include just spf2.bluehost.com
for all of the Bluehost services (assuming they're involved in sending mail). See the next section for how to advise Bluehost customers.
Solution for Bluehost customers
As noted in the previous section, start with this base (3 lookups):
v=spf1 a mx include:spf2.bluehost.com ~all
The final ~all
("soft failure") indicates mail recipients should be mildly dubious of —yet still deliver— mail that fails SPF. Set up DMARC to figure out what works and what is missed on the road to DMARC p=reject
(which will block all forged mail).
You'll have to add any hosted email or Email Service Provider(s) you use, plus any other hosts that you want to authorize to send mail on behalf of your domain.
In the case of this question, I see an explicit IP address and hosted mail by Google, so you'll need:
v=spf1 ip4:162.123.189.10 a mx include:spf2.bluehost.com
include:_spf.google.com ~all
Your total DNS lookup count is now seven and therefore your SPF is valid.