OK, that's done!
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PRODUCT, VERSION, MICROUPDATE, OPERATING SYSTEM, ARCHITECTURE
Parallels Plesk Panel 11.0 for Linux
PROBLEM DESCRIPTION
Plesk does not allow an underscore character in a CNAME entry
STEPS TO REPRODUCE
Go to Plesk control panel for domain Websites & Domains > DNS settings > Add record
Try adding a CNAME entry with an underscore
ACTUAL RESULT
Plesk reports "Error: Incorrect DNS record values were specified."
EXPECTED RESULT
Underscores should be allowed. This is required for DKIM to help email deliverability (in my case, using Amazon SES). Amazon says: "The rfc for hostnames disallows _ as a leading character, however this has been superceded by an RFC allowing _ for non-hostname application, such as DKIM (which requires CNAME records for DKIM to start with _domainkey). Unfortunately, a number of DNS providers don't closely follow the RFC. We added the _ to denote specifically that these are not host records and should not be treated as such and comply with rfc. The right thing is for the DNS providers to change their string parsing code."
ANY ADDITIONAL INFORMATION
As a workaround, I could add the CNAME entry in Plesk without an underscore, and then edit the file at /var/named/run-root/var. But this gets over-written every time Plesk does an update.
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