How to Split a DKIM Record
Security Boulevard, Friday, June 5th, 2026
A guide to splitting long 2048-bit DKIM keys into multiple quoted strings so they fit DNS TXT record limits.
This guide explains how to split a DKIM record when its public key exceeds the 255-character limit most DNS providers enforce on TXT record strings, a common issue with 2048-bit or longer keys that can otherwise be truncated or trigger errors.
The fix is to break the long value after the 'p=' tag into multiple chunks of 255 characters or fewer and enclose each chunk in double quotes within a single TXT record. DNS resolvers automatically concatenate these adjacent quoted strings back into the complete key during resolution.
Key formatting rules include not adding spaces between chunks, not reordering chunks, and not removing the semicolons separating DKIM tags. After publishing, the record should be validated using tools like dig or an online DKIM checker.