A DNS editor reporting a 255-character limit does not necessarily mean your SPF policy must become multiple records. The DNS TXT format allows multiple character-strings inside one resource record. SPF treats their contents as one continuous value. The operational challenge is to preserve the intended text while keeping the policy and its DNS responses manageable.
Separate three different limits
First, an individual TXT character-string is limited to 255 octets. SPF content is ASCII, so its ordinary characters each occupy one octet. A single TXT record can contain more than one such string. RFC 7208 section 3.3 explicitly permits that representation.
Second, the DNS response has a size. It includes names, record metadata and other TXT records returned at that owner name, not just SPF text. Section 3.4 recommends keeping SPF DNS answers small enough for legacy 512-octet UDP handling. This is a compatibility recommendation, not a universal 512-character maximum for SPF. Modern DNS transport capabilities do not eliminate every resolver, firewall or truncation problem.
Third, SPF evaluation has resource limits. Splitting text into strings does not reduce nested include processing or the ten lookup-causing-term limit. A short policy can exceed that evaluation limit; a longer list of explicit addresses may not. Assess syntax, DNS transport and evaluation cost independently.
Preserve spaces deliberately
SPF concatenates strings without inserting spaces. In a zone-file representation, "v=spf1 ip4:192.0.2.10 " "ip4:198.51.100.20 -all" produces the intended continuous policy because the first string ends with a space. Removing that space joins the two adjacent mechanisms into invalid text.
The documentation-only addresses above are illustrative. They are not authorised values for your domain. The quotation marks are zone-file presentation syntax; whether you enter them in a hosted DNS editor depends on that provider's documented interface. Some editors split long values automatically, while others expose separate string fields. Verify the served answer instead of assuming the editor's display matches the wire format.
Do not create a second TXT resource record beginning v=spf1 to hold the remainder. Multiple selected SPF records produce permerror. Conversely, do not delete unrelated TXT verification records because a diagnostic tool displays several TXT answers.
Inspect the published value
Capture the authoritative TXT response and identify which strings belong to each resource record. Reconstruct the SPF value by concatenating only the strings within its one record. Check spaces at every split boundary and ensure there is one version marker, valid mechanisms and the intended final statement.
Then test recursive DNS responses from the networks that matter. If a response is truncated or resolution fails, investigate DNS transport and provider configuration rather than deleting arbitrary mechanisms. DNSSEC and the wider answer set can affect response size; a simple character count is not a full packet-size test.
Prefer policy cleanup over clever packing
A growing policy often signals accumulated services. Review obsolete includes, unnecessarily broad mechanisms and duplicate authorisations before increasing complexity. Retain current provider-managed mechanisms when appropriate rather than copying their present IP addresses solely to shorten or reshape the record. Manually flattened addresses can become stale when providers change infrastructure.
For a policy that still needs multiple strings, save the intended unsplit text alongside the published representation. That gives future administrators a stable comparison target. A harmless editor reformat should not be confused with a semantic policy change.
Verify the reader-facing result
After an approved change, test representative sources and an unmatched source with a standards-aware evaluator, then inspect actual trusted receiver results. Record the reconstructed value, response observations and evaluation results. Close the issue when both DNS representation and authorisation behaviour are correct, not merely when the editor accepts the save.
Reconstruct a query answer
The following is a synthetic diagnostic exercise, not a query we ran or a record to publish. Substitute the actual SPF owner name and a verified authoritative nameserver before using these read-only commands. These templates use reserved example names.
dig @ns1.example.net example.com TXT +noall +answer
dig example.com TXT +noall +answerThe first command asks the specified authoritative server; the second uses the resolver configured on that machine. An answer from one recursive resolver does not prove that every receiver sees the same data. If needed, query another known resolver explicitly with @server-address.
Synthetic answer:
example.com. 300 IN TXT "v=spf1 ip4:192.0.2.10 " "ip4:198.51.100.20 -all"Reconstructed value:
v=spf1 ip4:192.0.2.10 ip4:198.51.100.20 -allWithout the trailing space in the first string, the boundary becomes 192.0.2.10ip4:198.51.100.20. The editor might accept the TXT data, but that does not make the SPF policy valid. By contrast, two separate answer records each starting v=spf1 are a multiple-policy problem, not a string-splitting solution.
Save the queried server, owner name, timestamp and answer. Reconstruct one record at a time, compare it with the intended unsplit policy, then evaluate sender authorisation separately. The commands inspect DNS representation; they do not run a complete SPF evaluation. See RFC 7208 Section 3.3 for concatenation and Section 4.6.4 for evaluation limits.