Plesk SPF Explanation is not returned.

[Tozz]

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Parallels Plesk Panel v11.5.30_build115130819.13 os_Debian 7.0), all MU's installed. x86_64

PROBLEM DESCRIPTION:
SPF Explanation is not returned to sender, nor in the logs.

STEPS TO REPRODUCE
Add SPF explanation (according to http://download1.parallels.com/Plesk/PP11/11.0/Doc/en-US/online/plesk-unix-cli/)
/opt/psa/bin/mailserver --update-spf -spf-exp "You message does not conform to the SPF policies"

ACTUAL RESULT
SMTP session is terminated with 550 5.7.1 Command rejected

SMTP Session snippet:
DATA
354 End data with <CR><LF>.<CR><LF>
Test
.
550 5.7.1 Command rejected

According to logs this is due to SPF failing (we have SPF policy set to reject):
Apr 30 09:27:52 rhea spf filter[6593]: Starting spf filter...
Apr 30 09:27:52 rhea spf filter[6593]: SPF result: fail
Apr 30 09:27:52 rhea spf filter[6593]: SPF status: REJECT

EXPECTED RESULT
I would expect the 550 5.7.1 rejection to contain the string "You message does not conform to the SPF policies"
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