dapper can't build itself: enigmail build depends failed

$ apt-get source enigmail --download-only
Reading package lists...
Building dependency tree...
Need to get 3149kB of source archives.
Get:1 http://megaera dapper-security/main enigmail 2:0.94-0ubuntu4.3 (dsc) [779B]
Get:2 http://megaera dapper-security/main enigmail 2:0.94-0ubuntu4.3 (tar) [3127kB]
using an up-to-date dapper
using an up-to-date pbuilder
the enigmail package can't build because dapper can't supply its build dependencies.
Log attached.

.......................................................

Get:3 http://megaera dapper-security/main enigmail 2:0.94-0ubuntu4.3 (diff) [21.3kB]
Fetched 3149kB in 21s (144kB/s)
Download complete and in download only mode

$ ls -l /tmp/pbuilder-wrapper-1175148083-270
total 3088
-rw-r--r-- 1 buildd buildd 21266 2007-02-23 22:04 enigmail_0.94-0ubuntu4.3.diff.gz
-rw-r--r-- 1 buildd buildd 779 2007-02-23 22:04 enigmail_0.94-0ubuntu4.3.dsc
-rw-r--r-- 1 buildd buildd 3126659 2006-02-15 17:04 enigmail_0.94.orig.tar.gz

$ sudo /usr/sbin/pbuilder build /tmp/pbuilder-wrapper-1175148083-270/enigmail_0.94-0ubuntu4.3.dsc
W: /home/buildd/.pbuilderrc does not exist
I: using fakeroot in build.
pbuilder-buildpackage/i386 $Id: pbuilder-buildpackage-funcs,v 1.28 2005/12/21 11:57:29 dancer Exp $
$Id: pbuilder-buildpackage,v 1.120 2006/01/06 12:30:51 dancer Exp $

Current time: Thu Mar 29 16:01:46 EST 2007
pbuilder-time-stamp: 1175148106
Building the build Environment
 -> extracting base tarball [/home/buildd/the-pbuilder-way/base.tgz]
 -> creating local configuration
 -> copying local configuration
 -> mounting /proc filesystem
ln: creating symbolic link `/home/buildd/the-pbuilder-way/build//25821/etc/mtab' to `../proc/mounts': File exists
 -> mounting /dev/pts filesystem
 -> policy-rc.d already exists
 -> created buildresult dir :/home/buildd/the-pbuilder-way/result/
Installing the build-deps
 -> Attempting to parse the build-deps : pbuilder-satisfydepends,v 1.22 2005/12/04 05:16:40 dancer Exp $
 -> Considering debhelper (>> 4.0.0)
   -> Trying debhelper
 -> Considering coreutils
   -> Trying coreutils
 -> Considering libidl-dev (>= 0.8.0 )
   -> Trying libidl-dev
 -> Considering zlib1g-dev
   -> Trying zlib1g-dev
 -> Considering docbook-to-man
   -> Trying docbook-to-man
 -> Considering zip
   -> Trying zip
 -> Considering dpatch
   -> Trying dpatch
 -> Considering m4
   -> Trying m4
 -> Considering mozilla-thunderbird-dev (>= 1.5.0.4)
      Tried versions: 1.5.0.2-0ubuntu2
   -> Does not satisfy version, not trying
E: Could not satisfy build-dependency.
E: pbuilder-satisfydepends failed.
 -> unmounting dev/pts filesystem
 -> unmounting proc filesystem
 -> cleaning the build env
    -> removing directory /home/buildd/the-pbuilder-way/build//25821 and its subdirectories

exit status 2