How to hand roll a message from a Nym

Introduction

Nymholders will frequently want to send messages from their Nym. Whilst it's quite easy to do this just by putting the Nym name in a From header, the message than lacks authenticity because it doesn't originate from the nymserver. Of course it's possible to digitally sign the outbound message with the Nym's PGP key but a better solution is to send the message via the Nymserver. This HowTo explains how to do that.

Prerequisites

Regardless of platform, you're going to need a text editor to create the message. Any good one will do but my preference is Vim which is available for most platforms.
You'll also need GnuPG to encrypt/sign messages. PGP is an alternative but lacks some of the features of GnuPG.
Lastly, you'll need Mixmaster to anonymously send your message to the Nymserver.

Writing the message

Open up your text editor and type an email, complete with headers for the recipient. That's the real recipient, not the nymserver. It should look something like this:
From: mynym@mixnym.net
To: a_recipient@somewhere.org
Subject: Testing

The content of the messages goes here.
Don't forget the blank like between headers and content, it's important!
Save the message as nymmsg (or any name of you prefer). You can then exit from the text editor.

Encrypting/Signing the message

The message now needs to be digitally signed and encrypted using GnuPG. The command to do this is:

gpg -asu mynym@mixnym.net -er send@mixnym.net nymmsg

This signs the message as mynym@mixnym.net and encrypts it to send@mixnym.net. The encrypted output (in ASCII format) is written to nymmsg.asc and will look something like this:
-----BEGIN PGP MESSAGE-----
Version: GnuPG v1.4.10 (GNU/Linux)

hQIOA37NSaIKEr1TEAf+OKKk/AenJLwBfSNqMGtR/FBbt0OMN1niTD/K831xt44M
XQVe/ek6hqIS/srTN25KA2NcS0Z73z+Z/iWzOm/SEsPoGFNoeCPJZqS5LDcQcpgK
DdzyvIEkTK6FQy0gYhpDzLhnNq7YTT4jRuhiowZVCacKi47fEYh/tsirMYJX4ubp
5SgtSqOlmpIo3AghmRjQG2P/8hSWFxVvkZH1wElbuF+Nu3ghQweJaG2wYGjp+Kux
PhlXxfJmYmOZgM2NbShEOgtBdRS+spJembDs1U87l0GLhJyJxZOGyeHElgi3Xn5r
E8eGXGLrdO16k70go0hy8xUD5E77wAWYtgmjWDGknaXoLKBt+M+F4q9you+esdxh
EYhk3saoFLlIlP0KRqN9X5i17BKQBgQCfiEpYMOOYm3M
=hnpH
-----END PGP MESSAGE-----

Sending the message with Mixmaster

Assuming you have Mixmaster configured for the Chains and Copies you want to use, the command to send the messages is:

mixmaster --mail send@mixnym.net nymmsg.asc

Here is a more complex command that uses a defined chain and number of copies:

mixmaster --mail -l *,*,dizum -c 2 send@mixnym.net nymmsg.asc

Cleaning up

You're done now so far as sending the message. If all goes well, you'll receive an achnowledgement in alt.anonymous.messages, encrypted to your key.

Don't forget you have a plain-text copy of the message in nymmsg on your machine. You may wish to delete it in a secure manner if the content is sensitive.