The remote host is missing an update to dovecot announced via advisory DSA 1516-1.

https://secure1.securityspace.com/smysecure/catid.html?in=DSA%201516-1

Prior to this update, the default configuration for Dovecot used by Debian runs the server daemons with group mail privileges. This means that users with write access to their mail directory by other means (for example, through an SSH login) could read mailboxes owned by other users for which they do not have direct write access (CVE-2008-1199). In addition, an internal interpretation conflict in password handling has been addressed proactively, even though it is not known to be exploitable (CVE-2008-1218). Note that applying this update requires manual action: The configuration setting mail_extra_groups = mail has been replaced with mail_privileged_group = mail. The update will show a configuration file conflict in /etc/dovecot/dovecot.conf. It is recommended that you keep the currently installed configuration file, and change the affected line. For your reference, the sample configuration (without your local changes) will have been written to /etc/dovecot/dovecot.conf.dpkg-new. If your current configuration uses mail_extra_groups with a value different from mail, you may have to resort to the mail_access_groups configuration directive. For the stable distribution (etch), these problems have been fixed in version 1.0.rc15-2etch4. For the unstable distribution (sid), these problems have been fixed in version 1.0.13-1. For the old stable distribution (sarge), no updates are provided. We recommend that you consider upgrading to the stable distribution.