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Syntax Recommendations Common Look Up mechanisms a: mx: include: ip4: ip6: exists: ptr: all Common Modifiers redirect= exp=   An A Record must ALWAYS contain IP address (map host to IP) CNAME (Alias) must contain hostnames. No IPs here NS an MX records must contain host names. No IPs allowed. MX records (for mail servers)  should contain hostnames NOT IPs. Too Many Mechanisms Section 10.1, "Processing Limits" of the SPF RFC 4408 specifies the following in regards to DNS lookups: 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. This limit is in place to prevent SPF lookups from being a useful avenue for Denial of Service attacks. Using an example SPF record as an example to illustrate, this record was breaking with 12 look-ups: example.com text = "v=spf1 include:_spf-a.example.com include:_spf-b.example.com include:_spf-c.example.com include:_spf-ssg-a.example.com include:spf-a.anotherexample.com ip4:131.107.115.215 ip4:131.107.115.214 ip4:205.248.106.64 ip4:205.248.106.30 ip4:205.248.106.32 ~all" [ 5 mechanisms] _spf-a.example.com  text = "v=spf1 ip4:216.99.5.67 ip4:216.99.5.68 ip4:202.177.148.100 ip4:203.122.32.250 ip4:202.177.148.110 ip4:213.199.128.139 ip4:213.199.128.145 ip4:207.46.50.72 ip4:207.46.50.82 a:mh.example.m0.net ~all"  [ +1 = 6 mechanisms] mh.example.m0.net a = 209.11.164.116 _spf-b.example.com text = "v=spf1 include:spf.messaging.example.com ip4:207.46.22.35 ip4:207.46.22.98 ip4:207.46.22.101 ip4:131.107.1.27 ip4:131.107.1.17 ip4:131.107.65.22 ip4:131.107.65.131 ip4:131.107.1.101 ip4:131.107.1.102 ip4:217.77.141.52 ip4:217.77.141.59 ~all" [+1 = 7 mechanisms] spf.messaging.example.com text = "v=spf1 include:spfa.anotherexample.com include:spfb.anotherexaple.com include:spfc.anotherexample.com -all"  [+3 = 10 mechanisms] spfa.anotherexample.com  text = "v=spf1 ip4:157.55.116.128/26 ip4:157.55.133.0/24 ip4:157.55.158.0/23 ip4:157.55.234.0/24 ip4:157.56.112.0/24 ip4:157.56.116.0/25 ip4:157.56.120.0/25 ip4:207.46.100.0/24 ip4:207.46.108.0/25 ip4:207.46.163.0/24 ip4:134.170.140.0/24 ip4:157.56.110.0/23 -all" [+0 = 10 mechanisms] spfb.anotherexample.com  text = "v=spf1 ip4:207.46.51.64/26 ip4:213.199.154.0/24 ip4:213.199.180.128/26 ip4:216.32.180.0/23 ip4:64.4.22.64/26 ip4:65.55.83.128/27 ip4:65.55.169.0/24 ip4:65.55.88.0/24 ip4:94.245.120.64/26 ip4:131.107.0.0/16 ip4:157.56.73.0/24 ip4:134.170.132.0/24 -all" [+0 = 10 mechanisms] spfc.anotherexample.com  text = "v=spf1 ip4:207.46.101.128/26 ip6:2a01:111:f400:7c00::/54 ip6:2a01:111:f400:fc00::/54 ip4:157.56.87.192/26 ip4:157.55.40.32/27 ip4:157.56.123.0/27 ip4:157.56.91.0/27 ip4:157.55.206.0/24 ip4:157.55.207.0/24 ip4:157.56.206.0/23 ip4:157.56.208.0/22 -all" [ +0 = 10 mechanisms] _spf-c.example.com  text = "v=spf1 ip4:203.32.4.25 ip4:213.199.138.181 ip4:213.199.138.191 ip4:207.46.52.71 ip4:207.46.52.79 ip4:131.107.1.18 ip4:131.107.1.19 ip4:131.107.1.20 ip4:131.107.1.48 ip4:131.107.1.56 ip4:86.61.88.25 ip4:131.107.1.44 ip4:131.107.1.37 ~all" [+0 = 10 mechanisms] _spf-ssg-a.example.com  text = "v=spf1 include:_spf-ssg-b.example.com include:_spf-ssg-c.example.com ~all"  [+2 = 12 mechanisms] _spf-ssg-b.example.com  text = "v=spf1 ip4:207.68.169.173/30 ip4:207.68.176.1/26 ip4:207.46.132.129/27 ip4:207.68.176.97/27 ip4:65.55.238.129/26 ip4:207.46.222.193/26 ip4:207.46.116.135/29 ip4:65.55.178.129/27 ip4:213.199.161.129/27 ip4:65.55.33.70/28 ~all"  [+0 = 12 mechanisms] _spf-ssg-c.example.com text = "v=spf1 ip4:65.54.121.123/29 ip4:65.55.81.53/28 ip4:65.55.234.192/26 ip4:207.46.200.0/27 ip4:65.55.52.224/27 ip4:94.245.112.10/31 ip4:94.245.112.0/27 ip4:111.221.26.0/27 ip4:207.46.50.221/26 ip4:207.46.50.224 ~all" [+0 = 12 mechanisms] spf-a.secondexample.com  text = "v=spf1 ip4:157.55.0.192/26 ip4:157.55.1.128/26 ip4:157.55.2.0/25 ip4:65.54.190.0/24 ip4:65.54.51.64/26 ip4:65.54.61.64/26 ip4:65.55.111.0/24 ip4:65.55.116.0/25 ip4:65.55.34.0/24 ip4:65.55.90.0/24 ip4:65.54.241.0/24 ip4:207.46.117.0/24 ~all" [+0 = 12 mechanisms] Character String Too Long 255 character limitation in a single string https://kb.isc.org/article/AA-00356/0/Can-I-have-a-TXT-or-SPF-record-longer-than-255-characters.html http://www.string-functions.com/length.aspx You may have more than 255 characters of data in a TXT or SPF record, but not more than 255 characters in a single string. If you attempt to create an SPF or TXT record with a long string (>255 characters) in it, BIND will give an error (e.g. "invalid rdata format: ran out of space".)  Strings in SPF and TXT records should be no longer than 255 characters.  However to get around this limitation, per RFC 4408 a TXT or SPF record is allowed to contain multiple strings, which should be concatenated together by the reading application.  In the case of use for SPF (using either TXT or SPF RRs) the strings are concatenated together without spaces as described below.  Reassembly by other applications of multiple strings stored in TXT records might work differently. 3.1.3. Multiple Strings in a Single DNS record As defined in [RFC1035] sections 3.3.14 and 3.3, a single text DNS record (either TXT or SPF RR types) can be composed of more than one string. If a published record contains multiple strings, then the record MUST be treated as if those strings are concatenated together without adding spaces. For example: IN TXT "v=spf1 .... first" "second string..." MUST be treated as equivalent to IN TXT "v=spf1 .... firstsecond string..." SPF or TXT records containing multiple strings are useful in constructing records that would exceed the 255-byte maximum length of a string within a single TXT or SPF RR record. EXAMPLE text = "v=spf1 ip4:199.15.212.0/22 ip4:72.3.185.0/24 ip4:72.32.154.0/24 ip4:72.32.217.0/24 ip4:72.32.243.0/24 ip4:94.236.119.0/26  ip4:37.188.97.188/32 ip4:185.28.196.0/22 ~all“ text = "v=spf1 ip4:199.15.212.0/22“ " ip4:72.3.185.0/24 ip4:72.32.154.0/24 ip4:72.32.217.0/24" " ip4:72.32.243.0/24 ip4:94.236.119.0/26" " ip4:37.188.97.188/32 ip4:185.28.196.0/22 ~all" Null Records in the SPF Record A record that is NULL or that does not exist will break an SPF record.  Syntax within the record is very important, if there are extra spaces between mechanisms it will count as NULL. EXAMPLE text = "v=spf1 ip4:199.15.212.0/22“ <- accurate text = "v=spf1 ip4: 199.15.212.0/22“ <- NULL (NOTE the space between IP4: and the IP) Repetitive Records in the SPF Record - Void Lookups If there are too many repetitive mechanisms in the SPF record, including records that cascade (for example when using "include:") the record will break. There is a MAX of 2 void look ups in an SPF record.  More than that and the record will break.  This prevents SPF records from being used in Denial of Service style attacks. Validation Tools SPF checker, syntax validator and SPF tester http://www.kitterman.com/spf/validate.html SPF checker http://vamsoft.com/support/tools/spf-policy-tester SPF validator http://vamsoft.com/support/tools/spf-syntax-validator CIDR Calculator http://www.subnet-calculator.com/cidr.php Nslookup http://network-tools.com/nslook/ SPF creation wizard http://www.microsoft.com/mscorp/safety/content/technologies/senderid/wizard/ Common SPF errors http://www.openspf.org/FAQ/Common_mistakes SPF syntax definitions http://www.openspf.org/SPF_Record_Syntax

No, unfortunately we are unable to tell you what the spam trap address is. We don’t even know it ourselves! Spam trap addresses are proprietary to the blacklists that own them. Anti-spam professionals use spam trap addresses to track unsolicited emails. If a spam trap is known by the offending sender, the sender could simply remove the spam trap address from their lists and never actually address the data problem that caused that spam trap address to be included in their lists to begin with. Instead of asking what the spam trap address is, try to identify the source of the trap address and eliminate bad data sources from your mailing lists. You should be able to identify the email campaign that caused the blacklist issue, so you should start with those lists. To narrow it down and identify the problematic data source, you should consider the following: Have you recently added any new leads or new lead sources? What is the source of these leads? Any purchased or appended email addresses should be removed, because these data sources are often the source of newly introduced spamtraps. In addition, using purchased or appended email addresses for mailing is a violation of Marketo’s Email Use and Anti-Spam Policy. Have you added any older leads that have not been mailed to recently? Some email providers will turn an email address into a spam trap after a year of inactivity. If you have a list of addresses that has not been mailed to in a year or more, this list should be removed. Does your system use any custom fields to indicate customer status, event attendance, recent contact with your sales team, or other forms of engagement? If so, take advantage of this and isolate the inactive or non-responsive segments of your database using all of the activity data you have available. Is there anything about this specific mailing that makes it different compared to your previous email campaigns? Did you send any other mail on the same day? If so, you should compare the recipient lists. Think you have narrowed in on the problem? Check out our guide to blacklist remediation to find out what to do with that bad list and complete the remediation program.   Additional Resources: What is a spamtrap, or spam trap, and why does it matter? What is a blacklist? How does Marketo respond to blacklisting and spam notifications? Top blacklists - What you need to know Blacklist Remediation Successful Reconfirmation Blacklist Deep Dive Blacklist FAQ   Is this article helpful ? YesNo