[Dovecot] managesieve vacation script bounces/frozen with a 550 error.

[Jason X, Maney]

Dear all,

I have been trying to get this problem out of the way but I just cant seem
to get it right. I hope someone can point me in the right direction here. I
have come up with a vacation script as below, which can be send out from my
Postfix SMTP server to my smarthost at the ISP, and yet for some reason it
is not sent out at my ISP server. The guys at the ISP have sent me the full
error they are getting on their Exim SMTP server. My dovecot version is:
==========
dovecot --version
1.2.9
==========

...and my managesieve configs are as follows:
==========
dovecot -n |grep sieve
protocols: pop3 pop3s imap imaps managesieve
listen(managesieve): *:4190
login_executable(managesieve): /usr/lib/dovecot/managesieve-login
mail_executable(managesieve): /usr/lib/dovecot/managesieve
mail_plugins(managesieve):
mail_plugin_dir(managesieve): /usr/lib/dovecot/modules/managesieve
  mail_plugins: sieve quota
  sieve: /var/vmail/sieve/%d/%u/sieve-script
  sieve_global_path: /var/vmail/sieve/default.sieve
  sieve_storage: /var/vmail/sieve/%d/%u
==========

Error from my ISP smarthost:
==========
+++ 1ReM7W-000Dm8-My has not completed +++
2011-12-26 09:34:18 1ReM7W-000Dm8-My <= <>
H=(myhostname.mydomain.com<http://havana.Speedlinkcargo.com>)
[xxx.xxx.xxx.xxx] P=esmtps X=TLSv1:DHE-RSA-AES256-SHA:256 S=1451
id=dovecot-sieve-1324712058-257846-0 at havana T="Out of office reply"
2011-12-26 09:34:18 1ReM7W-000Dm8-My **
jsxmoney at gmail.comR=send_to_gateway T=remote_smtp: SMTP error from
remote mail server after
RCPT TO:<jsxmoney at gmail.com>: host
smtp.myisp.com<http://smtp2.yoafrica.com>[yyy.yyy.yyy.yyy]: 550
Bounces must have only a single recipient
2011-12-26 09:34:18 1ReM7W-000Dm8-My Frozen (delivery error message
==========

My vacation sieve script is:
==========
## /* empty script */
require ["fileinto", "vacation"];

vacation
  # Reply at most once a day to a same sender
  :days 1
  :subject "Out of office reply"
  # List of additional recipient addresses which are included in the auto
replying.
  # If a mail's recipient is not the envelope recipient and it's not on
this list,
  # no vacation reply is sent for it.
  :addresses "me at mydomain.com"
"I'm out of office, please contact Joan Doe instead.
Best regards
Me";
==========

What I am not sure of is, is this a problem I need to fix or is it
something my ISP need to work on, on their Exim? If its something they can
work on can you also give me pointers so I can work with them to fix it?

Many thanx,

JXM.