xB Mail: Anonymous Email Client

[Arrakis]

I am writing an anonymous email client. The main
delay has been getting it compatible with the xerobank
installer so that it automatically downloads mail
credentials and creates the secmod/key3/cert8 PKCS11
databases and performs automatic encryption of the
user credentials, locking it with the users' PIN code
as the master password.

The design idea is to use an anonymous email server
/ service, or to take any freemail provider and turn
it into an anonymous account (assuming a clean acct).

So I decided while I picked up a cold at defcon that
I would sit down and finally finish it. It works.

It is built using Mozilla Thunderbird. It will contain
the Enigmail extension, and a self-contained GPG
distribution. It will probably also contain NoScript
because it has an html renderer inside it. The program
already has a built-in auto-updater from xerobank that
will download and install it's own PGP signed updates.
The enigmail will be configured to use 5+ keyservers
such as mit, sks, pgp, etc.

The threat model includes content and context obscurity.

Where this meets Tor and anonymity is the question. It
is my intention to filter by protocol, blocking all
communication that is not using either SSL or TLS. Are
there any other considerations we should have, other
than blocking updates? Should we force OCSP and cert
revokation checking? Is there any reason we shouldn't
include the CACert root certificate? Should we scrap
Tor and make it use mixmaster? Should we force users
to create/import PGP Keypairs?

The more I understand email threats/issues over Tor
the better. I am aware that there are only occasionally
any exit servers allowing port 25, but if we are
forcing SSL/TLS, then it won't matter what port they
pick. So any preferences for extensions and behavior are
welcome.

Suggestions will be used to craft an opensource software
released under TESLA license which prevents malware /
spyware additions, and unauthorized modification for
the purpose of commercial profit.

This program will be completed today, and ready for
testing tomorrow, so the sooner I get comments the
better.

Arrakis