Vacation problem

[dimon at intellinetinc.com]

Hello,

I have Cyrus IMAP + Sendmail installed
in my imapd.conf ia have
duplicatesuppression: yes
sieveusehomedir: false
sievedir: /var/imap/sieve
sendmail: /usr/sbin/sendmail
postmaster: postmaster
sieve_maxscriptsize: 32
sieve_maxscripts: 50

And everything works fine, except for vacation message sending back to sender.

This is the part of my maillog:

Jan 22 14:54:34 synodon sm-mta[10247]: h0MLsXHp010247: 
from=<dmitry at montanaband.net>, size=882, class=0, nrcpts=1, 
msgid=<1043272470.3e2f131700aa7 at webmail.montanaband.net>, proto=ESMTP, 
daemon=MTA, relay=[198.161.98.157]
Jan 22 14:54:46 synodon sm-mta[10255]: h0MLsXHp010247: to=<dmitry at synodon.com>, 
delay=00:00:12, xdelay=00:00:00, mailer=cyrusv2, pri=30872, relay=localhost, 
dsn=2.0.0, stat=Sent
Jan 22 14:55:42 synodon sm-mta[10261]: h0MLtgHp010261: from=<dmitry at montana-
education.ab.ca>, size=954, class=0, nrcpts=1, 
msgid=<1043272535.3e2f13577dcc8 at webmail.montana-education.ab.ca>, proto=ESMTP, 
daemon=MTA, relay=[198.161.98.159]
Jan 22 14:55:46 synodon sendmail[10271]: h0MLtkqQ010271: Authentication-
Warning: synodon.com: cyrus set sender to <> using -f
Jan 22 14:55:46 synodon sendmail[10271]: h0MLtkqQ010271: from=<>, size=312, 
class=0, nrcpts=1, msgid=<cmu-sieve-10270-1043272546-0 at synodon.com>, 
relay=cyrus at localhost
Jan 22 14:55:47 synodon sm-mta[10272]: STARTTLS=server, relay=localhost 
[127.0.0.1], version=TLSv1/SSLv3, verify=NO, cipher=EDH-RSA-DES-CBC3-SHA, 
bits=168/168
Jan 22 14:55:47 synodon sendmail[10271]: STARTTLS=client, relay=[127.0.0.1], 
version=TLSv1/SSLv3, verify=FAIL, cipher=EDH-RSA-DES-CBC3-SHA, bits=168/168
Jan 22 14:55:47 synodon sm-mta[10272]: h0MLtkHq010272: from=<>, size=548, 
class=0, nrcpts=1, msgid=<cmu-sieve-10270-1043272546-0 at synodon.com>, 
proto=ESMTP, daemon=MTA, relay=localhost [127.0.0.1]
Jan 22 14:55:50 synodon sendmail[10271]: h0MLtkqQ010271: to=dmitry at montana-
education.ab.ca, delay=00:00:04, xdelay=00:00:04, mailer=relay, pri=30307, 
relay=[127.0.0.1] [127.0.0.1], dsn=2.0.0, stat=Sent (h0MLtkHq010272 Me
ssage accepted for delivery)
Jan 22 14:55:50 synodon sm-mta[10269]: h0MLtgHp010261: to=<dmitry at synodon.com>, 
delay=00:00:08, xdelay=00:00:0
4, mailer=cyrusv2, pri=30944, relay=localhost, dsn=2.0.0, stat=Sent
Jan 22 14:55:50 synodon sm-mta[10280]: h0MLtkHq010272: to=<dmitry at montana-
education.ab.ca>, delay=00:00:03, xdelay=00:00:00, mailer=esmtp, pri=30543, 
relay=mail.montana-education.ab.ca. [198.161.98.159], dsn=5.0.0, stat=
Service unavailable
Jan 22 14:55:50 synodon sm-mta[10280]: h0MLtkHq010272: h0MLtoHp010280: 
postmaster notify: Service unavailable
Jan 22 14:55:50 synodon sm-mta[10280]: h0MLtoHp010280: 
to=dmitry at intellinetinc.com, delay=00:00:00, xdelay=00:
00:00, mailer=esmtp, pri=31757, relay=mail.intellinetinc.com. [139.142.54.37], 
dsn=5.0.0, stat=Service unavailable
Jan 22 14:55:50 synodon sm-mta[10280]: h0MLtoHp010280: h0MLtoHq010280: return 
to sender: Service unavailable
Jan 22 14:55:50 synodon sm-mta[10280]: h0MLtoHq010280: 
to=dmitry at intellinetinc.com, delay=00:00:00, xdelay=00:00:00, mailer=esmtp, 
pri=32781, relay=mail.intellinetinc.com., dsn=5.0.0, stat=Service unavailable
Jan 22 14:55:50 synodon sm-mta[10280]: h0MLtoHp010280: 
Losing ./qfh0MLtoHp010280: savemail panic
Jan 22 14:55:50 synodon sm-mta[10280]: h0MLtoHp010280: SYSERR(root): savemail: 
cannot save rejected email anywhere

So, the sender never gets the vacation message.
I'm wondering why cyrus setting sender to <>, not to <dmitry at synodon.com>, or 
even <postmaster> as I made configuration in my imapd.conf?
May be I missed something?
What could be done to fix that problem?

Thanks,
Dmitry