[SM-USERS] Request receipt acknowledge failure

[tovis <dai...@fr...>]

Hi!

When I've get request to acknowledge, and use to be click on "OK" I've get
"Mail Delivery System", contain:

Message 1KoYo9-00070N-Qa has been frozen (delivery error message).
The sender is <>.

The following address(es) have yet to be delivered:
  dai...@fr...: SMTP error from remote mail server after RCPT
TO:<dai...@fr...>: host smtp.upcmail.hu [213.46.255.2]: 550 5.1.1
<dai...@fr...> recipient rejected

Header:

Return-path: <>
Envelope-to: pos...@bo...
Delivery-date: Sat, 11 Oct 2008 09:22:40 +0200
Received: from Debian-exim by boci.kuku-lab.dyndns.ws with local (Exim 4.63)
     id 1KoYoB-00070Q-VI
     for pos...@bo...; Sat, 11 Oct 2008 09:22:39 +0200
Auto-Submitted: auto-replied
From: Mail Delivery System <Mai...@bo...>
To: pos...@bo...
Subject: Message frozen
Message-Id: <E1K...@bo...>
Date: Sat, 11 Oct 2008 09:22:39 +0200

Details:
  Squirrelmail version 1.4.9a
  Plugins: message_details, info, abook_take

  PHP5: php5.2.0-8+etch13
    I'm not sure that is it the cure, but I have been upgraded
    my server Etch at 2008.10.09 with packages:
      libapache2-mod-php5 php5 php5-common php5-recode
    I'm sure that some weeks ago this feature is worked well!
    I do not know how to step back, for previouse version of
    these packages :(

  WEB server: Apache 2.2.3-4+etch5
  IMAP server: Courier 4.1.1.20060828-5
  SMTP server: Exim4 4.63-17 (daemon-heavy)
    using smarthost, I do not have own MX record!
  Server: Debian/Linux Etch (stable)
  Kernel 2.6.18-6-686 #1 SMP
  Client(s) winXP prof HU and Firefox 2.0.x and 3.0.x

What could be wrong?