More and more organizations are moving from the shorter 384, 512 and 768-bit keys up to 1024 and higher in order to protect against spoofing because the smaller keys are easier to crack. Our DNS system intuitively supports a 2048-bit key and larger. Simply paste it into the TXT record and hit save. Our back-end systems do what’s needed to break it up into 255 byte chunks to comply with RFC 1035, section 2.3.4 so you don’t have to do anything.
You can test your DKIM after creating it using the handy tool here: http://dkimcore.org/c/keycheck
This tool will show you how it joins the two parts into one key.
If you encounter any issues, please feel free to submit a support ticket. We’re here 24×7 to help!