The remote host is missing an update to balsa announced via advisory DSA 300-1.

https://secure1.securityspace.com/smysecure/catid.html?in=DSA%20300-1

Byrial Jensen discovered a couple of off-by-one buffer overflow in the IMAP code of Mutt, a text-oriented mail reader supporting IMAP, MIME, GPG, PGP and threading. This code is imported in the Balsa package. This problem could potentially allow a remote malicious IMAP server to cause a denial of service (crash) and possibly execute arbitrary code via a specially crafted mail folder. For the stable distribution (woody) this problem has been fixed in version 1.2.4-2.2. The old stable distribution (potato) does not seem to be affected by this problem. For the unstable distribution (sid) this problem will be fixed soon. We recommend that you upgrade your balsa package.