[Dovecot] lmtp weird error: Bad address

[Paweł Madej]

>From time to time for one of email addresses i got such error. Have no 
idea why, as it is valid. Dovecot 2.0.2

Oct  6 17:37:52 postfix/smtpd: connect from unknown[212.xxx.101.5]
Oct  6 17:37:52 postfix/smtpd: setting up TLS connection from 
unknown[212.xxx.101.5]
Oct  6 17:37:53 postfix/smtpd: Anonymous TLS connection established 
from unknown[212.xxx.101.5]: TLSv1 with cipher DHE-RSA-AES256
-SHA (256/256 bits)
Oct  6 17:37:53 sqlgrey: grey: from awl match: updating 
212.xxx.101(212.xxx.101.5), from at example.com(from at example.com)
Oct  6 17:37:59 postfix/policyd-weight: decided action=DUNNO  using 
cached result; rate: -2.3; <client=212.xxx.101.5> 
<helo=mx1.example.com> <from=from at example.com> <to=to at example.com>; 
delay: 6s
Oct  6 17:37:59 postfix/smtpd: 9CD23A9C6BD: 
client=unknown[212.xxx.101.5]
Oct  6 17:37:59 postfix/cleanup: 9CD23A9C6BD: 
message-id=<4cac977f4c58d7.89836790 at example.com>
Oct  6 17:37:59 postfix/qmgr: 9CD23A9C6BD: from=<from at example.com>, 
size=1967, nrcpt=1 (queue active)
Oct  6 15:37:59 postfix/smtpd: disconnect from unknown[212.xxx.101.5]
Oct  6 17:38:00 postfix/smtpd: connect from 
localhost.localdomain[127.0.0.1]
Oct  6 17:38:00 postfix/smtpd: 39179A9C886: 
client=localhost.localdomain[127.0.0.1]
Oct  6 17:38:00 postfix/cleanup: 39179A9C886: 
message-id=<4cac977f4c58d7.89836790 at example.com>
Oct  6 17:38:00 postfix/qmgr: 39179A9C886: from=<from at example.com>, 
size=2335, nrcpt=1 (queue active)
Oct  6 17:38:00 dovecot: lmtp(12184): Connect from local
Oct  6 17:38:00 dovecot: lmtp(12184, to at example.com): Error: 
lstat((null)) failed: Bad address
Oct  6 17:38:00 dovecot: lmtp(12184, to at example.com): Error: 
file_dotlock_create((null)) failed: Bad address
Oct  6 17:38:00 dovecot: lmtp(12184, to at example.com): Error: 
open((null)) failed: Bad address
Oct  6 17:38:00 postfix/smtpd: disconnect from 
localhost.localdomain[127.0.0.1]
Oct  6 17:38:00 postfix/lmtp: 9CD23A9C6BD: to=<to at example.com>, 
relay=my.relay[/var/run/dspam/dspam.sock],
delay=7.3, delays=6.8/0/0/0.53, dsn=2.6.0, status=sent (250 2.6.0 
<to at example.com> Message accepted for delivery)
Oct  6 17:38:00 postfix/qmgr: 9CD23A9C6BD: removed

Message is delivered properly but i got such errors and have no idea 
why.
I've searched google for this but noone have answer for my problem.

Greets
--
Paweł Madej