[Exim] Exim SMTP protocol violation/bug

I use a verify-only router to reject some often used spam-addresses during
SMTP time:

bad_addresses:
        driver = redirect
        data = ${lookup{$local_part@$domain}lsearch{CONFDIR/bad_addresses}
{:fail:$value}fail}
        allow_fail
        verify_only
        fail_verify

CONFDIR/bad_addresses contains simply this:

localpart1@domain1
localpart2@domain2:    Address abused for spam

i.e., some addresses are followed by an explanatory text, some are not.

When I do a test with the first address:

MAIL FROM:<localpart1@domain1>
250 OK
RCPT TO:<some@address>
550 Verification failed for <localpart1@domain1>
550 Sender verify failed

These latter two lines are a violation of the SMTP standard, I think.
Shouldn't the first 550 be followed by a '-'?

When I test with the second address, it's ok though:

MAIL FROM:<localpart2@domain2>
250 OK
RCPT TO:<some@address>
550-Verification failed for <localpart2@domain2>
550-Address abused for spam
550 Sender verify failed

This is Exim 4.24.

--
Mark

mark@???