Attached please find a patch proposal which solves the issue.
Saluti,
Benjamin
--- inn-2.5.2-debian/debian/rules 2010-05-17 20:57:05.803848629 +0200
+++ inn-2.5.2/debian/rules 2010-05-17 20:43:13.053870834 +0200
@@ -102,6 +102,7 @@
--with-sasl=/usr \
--with-sendmail=/usr/sbin/sendmail \
--with-zlib=/usr \
+ --with-openssl \
$($*_configure_flags) $(configure_flags)
touch $@
