Reply code 051 and 050 from VRFY

Hello, playing around with sendmail's VRFY command I encountered the
following:

vrfy deleted-account@lex911.ru
051 lex911.ru: Name server timeout
050 deleted-account@lex911.ru... Transient parse error -- message
queued for future delivery
252 2.1.5 <deleted-account@lex911.ru>

Well, RFC2821 does not define 1st digit of code equal to zero at all.
Sec 4.2 last sentence "Consequently, a sender-SMTP MUST be prepared to
handle codes not
specified in this document and MUST do so by interpreting the first
digit only." Though, sec 4.2.1 does not define 0yz.

I do like the extra information in 051, so I can skip the rest of
processing, but is there a documentation about these extra replies
somewhere?

BTW: grepping the code, there is a single hit in sendmail v8.14.3:
../libsmutil/safefile.c: message("051 WARNING: %s writable directory
%s",
However, I use Debian's v8.13.8-3

Regards,

In article
<c815c2d4-d685-4cf8-8ec8-12612f0cd368@b1g2000hsg.googlegroups.com> ska
<skg@mail.inf.fh-brs.de> writes:
>Hello, playing around with sendmail's VRFY command I encountered the
>following:
>
>vrfy deleted-account@lex911.ru
>051 lex911.ru: Name server timeout
>050 deleted-account@lex911.ru... Transient parse error -- message
>queued for future delivery
>252 2.1.5 <deleted-account@lex911.ru>

It seems you are running the daemon in debug mode (-dx.y, maybe -v will
have this effect too). Don't do that on a production server - SMTP
clients will be completely confused not just by the non-standard 0xx
codes, but also by the fact that multiple responses are given for a
single command.

--Per Hedeland
per@hedeland.org