Why does my BIMI DNS record return an unexpected string instead of the correct value?
Matthew Whittaker
Co-founder & CTO, Suped
Published 16 Apr 2025
Updated 19 Aug 2025
7 min read
Encountering an unexpected string when querying your Brand Indicators for Message Identification (BIMI) DNS record can be puzzling. Instead of seeing the familiar v=BIMI1; l=... syntax, you might get a seemingly random alphanumeric sequence. This usually indicates an underlying configuration problem with your DNS setup, preventing the correct BIMI record from being retrieved or interpreted. I've encountered this issue before and it can definitely be a head-scratcher.
A correctly published BIMI record is crucial for displaying your brand logo in supporting email clients. When the record returns an unexpected string, it means the validation process fails, and your logo won't appear, undermining your brand’s visibility. This directly impacts how your brand is perceived by recipients and can even affect email trust.
This guide explores the common reasons why your BIMI DNS record might return an unexpected string and provides practical steps to diagnose and fix the issue. We'll look into common syntax errors, DNS conflicts, and other factors that could lead to this puzzling behavior.
Understanding BIMI DNS records
BIMI records are published as TXT records in your Domain Name System (DNS). They contain information that mail servers use to verify your brand's identity and display your logo. The basic structure includes a version tag and a URL pointing to your SVG logo file.
A typical BIMI DNS TXT record follows a precise format. It starts with v=BIMI1 to specify the version, followed by a semicolon and then the location of your logo using l= and the URL to your Brand Indicator SVG file. For BIMI to work, your domain must also have a DMARC policy enforced at quarantine or reject. This ensures that your email authentication is strong enough for participating mail providers to trust your logo.
Example BIMI DNS TXT Record
default._bimi.yourdomain.com IN TXT "v=BIMI1; l=https://yourdomain.com/images/brandlogo.svg; a=https://yourdomain.com/path/to/vmc.pem"
The a= tag, though optional, points to your Verified Mark Certificate (VMC). A VMC provides an additional layer of trust and is often required by major email clients, like Gmail, for BIMI logo display. Without it, your logo might not appear in all inboxes, even if the record is otherwise correct. If your BIMI logo isn't showing, a missing or invalid VMC can be a common culprit.
Common causes of unexpected string values
When your BIMI DNS record returns an unexpected string, it's often due to subtle configuration errors. One of the most common issues I see is incorrect syntax. Even a single misplaced character, like an extra semicolon or a missing quote, can corrupt the entire record string. DNS resolvers are very particular about the exact formatting of TXT records.
Common syntax errors
A frequent mistake is adding an unintended character at the end of the URL or within the string, such as a trailing semicolon. While BIMI records use semicolons to separate tags, they should not appear arbitrarily. Additionally, ensuring your BIMI record's syntax matches the official specification is critical for correct interpretation.
DNS conflicts and overrides
Another significant cause is a conflict with other DNS records. A wildcard TXT record (* TXT) can sometimes override more specific records, causing an unexpected string to be returned for subdomains. Similarly, having a CNAME record on the same subdomain as your BIMI TXT record can lead to issues, as CNAMEs cannot coexist with other record types on the same host name. These hidden conflicts are particularly tricky to diagnose without full DNS access.
Some DNS providers may have limitations on the length of TXT records. If your BIMI record string exceeds these limits, it might be truncated or stored incorrectly, leading to an unexpected output. This is a known issue with certain DNS services, and it's something I've seen impact Amazon SES DKIM records as well. You might receive a "CharacterStringTooLong" error or simply see a corrupted string, as described in troubleshooting guides.
Troubleshooting unexpected BIMI outputs
Diagnosing why your BIMI DNS record returns an unexpected string requires a systematic approach. The first step is always to verify the exact record that is being returned by DNS queries. You can use command-line tools like dig or nslookup to perform a DNS lookup for your BIMI TXT record. This will show you exactly what external resolvers are seeing.
Example dig command for BIMI TXT recordbash
dig TXT default._bimi.yourdomain.com +short
Once you have the returned string, compare it meticulously against the BIMI specification. Look for any unintended characters, missing quotes, or incorrect spacing. Remember, even a single character can throw off the entire record. If you are struggling with this, a BIMI validation tool can often highlight specific syntax errors.
Next, investigate potential DNS conflicts. Check your DNS zone file for any wildcard TXT records (* TXT) that might be overriding your specific BIMI entry. Also, confirm that there are no CNAME records set for default._bimi.yourdomain.com. If a CNAME exists, it must be removed, as it prevents other record types from being present for that hostname. Finally, consult your DNS provider's documentation or support to understand any TXT record length limitations or unique behaviors that could affect your BIMI record.
Preventative measures and best practices
To prevent your BIMI DNS record from returning an unexpected string, proactive measures and diligent record management are essential. Ensuring your email authentication is solid from the start is paramount.
Verify syntax: Always double-check your BIMI record against the official specifications before publishing. Use a reliable online validator to catch any syntax errors immediately.
Check for conflicts: Before adding your BIMI record, scan your DNS zone for any existing wildcard TXT records or CNAMEs that could conflict with or override the BIMI entry.
Review DNS provider limits: Familiarize yourself with your DNS provider's specific rules regarding TXT record lengths and any other unique behaviors that might affect BIMI.
Monitor regularly: Even after successful setup, periodically check your BIMI record to ensure it remains valid and resolves correctly. DNS changes can sometimes introduce unforeseen issues.
Having a robust email authentication foundation is key to BIMI success. Ensure your domain has correctly configured SPF, DKIM, and DMARC records. A DMARC policy set to enforcement (p=quarantine or p=reject) is a prerequisite for BIMI to be honored by most mailbox providers. Without strong authentication, your BIMI logo won't display, regardless of your record's syntax.
Finally, if your BIMI logo is not showing up, remember to check not only the DNS record but also the SVG image itself. The SVG file must adhere to specific formatting requirements to be valid for BIMI. Issues with the SVG, such as incorrect sizing or unapproved elements, can also prevent your logo from appearing, even if the DNS record is perfect. There are tools available specifically for validating your BIMI SVG and certificate.
Views from the trenches
Best practices
Always validate your BIMI DNS TXT record using an online checker before and after publishing to catch any syntax errors early.
Ensure your DNS provider does not have hidden wildcard records that might unexpectedly override your specific BIMI entry.
Double-check that the URL in your BIMI record points directly to a properly formatted and publicly accessible SVG file.
Confirm that your DMARC policy is set to 'quarantine' or 'reject' for the domain, as this is a prerequisite for BIMI adoption.
Common pitfalls
Adding extraneous characters, like a trailing semicolon, to the URL within the BIMI TXT record string.
Having a CNAME record on the same subdomain as your BIMI TXT record, which causes conflicts and prevents proper resolution.
Ignoring the maximum TXT record length limits imposed by some DNS providers, leading to truncation or unexpected values.
Assuming that a correctly configured BIMI record alone will suffice without validating the associated SVG image and VMC.
Expert tips
Use command-line tools such as 'dig' to query your DNS records directly, which can help reveal any unexpected outputs or conflicting entries.
Be aware that some DNS systems might append their own characters or modify strings if the record is not properly quoted or escaped.
If your DNS provider is Amazon Route 53, specific knowledge of their TXT record handling for longer strings can be crucial for debugging.
Always consult your DNS provider's documentation or support if you suspect an unusual behavior in record propagation or interpretation.
Expert view
Expert from Email Geeks says the URL for the image might be broken, so checking that it points to the correct location is a good first step when debugging BIMI issues.
2023-01-15 - Email Geeks
Marketer view
Marketer from Email Geeks says that an extra semicolon at the end of the URL in the BIMI record string caused the unexpected output, a small detail that can easily be overlooked.
2023-03-20 - Email Geeks
Ensuring your brand appears correctly
Dealing with an unexpected string from your BIMI DNS record can be frustrating, but it's typically a fixable issue related to DNS configuration or syntax. By carefully verifying your record's content, checking for conflicts, and understanding your DNS provider's specific behaviors, you can resolve most problems.
Remember that BIMI relies on a strong foundation of email authentication, including SPF, DKIM, and an enforced DMARC policy. Ensuring these are correctly set up is just as important as the BIMI record itself for your brand logo to appear consistently in inboxes. Persistent issues might require deeper investigation into your DNS infrastructure or consulting with your DNS provider.
With the right approach, you can ensure your BIMI record resolves correctly, allowing your brand to benefit from increased visibility and trust in your email communications.
Gmail, for BIMI logo display. Without it, your logo might not appear in all inboxes, even if the record is otherwise correct. If your BIMI logo isn't showing, a missing or invalid VMC can be a common culprit.
Amazon SES DKIM records as well. You might receive a "CharacterStringTooLong" error or simply see a corrupted string, as described in troubleshooting guides.
