TXT Record Too Long? How to Split DKIM for DNS Providers
255-character limits, quoting, and paste errors that break DKIM verification.
DKIM public keys exceed one TXT string on some panels. Learn how to split records or use your provider's long-string UI without breaking verification.
Why DKIM keys hit the limit
A single string inside a DNS TXT records (short text lines in DNS used for email security) can hold at most 255 characters. A 2048-bit DKIM public key — the size OquMail generates — is longer than that once it is written out. The record itself can be longer; it just has to be stored as several strings that receivers join back together.
How DNS panels handle it
- Many panels, including Cloudflare, accept the full value and split it for you
- Some, such as Amazon Route 53 and BIND zone files, expect you to enter it as several quoted strings in one record
- A few panels silently cut the value at 255 characters — the record then exists but verification fails
Splitting it by hand
Break the value into chunks of 255 characters or fewer, wrap each chunk in double quotes and put them in the same record, separated by a space. Do not add spaces inside the key itself.
"v=DKIM1; k=rsa; p=MIIBIjANBgkqh...first part..." "...second part...IDAQAB"Check the result
Look up the record (for example with nslookup -type=txt selector._domainkey.yourdomain.com) and confirm the joined value matches what OquMail shows, character for character. Then press Verify on the domain page.