ssh tunnel for smtp

For details see: http://cg.scs.carleton.ca/~morin/misc/laptopmail/

local - where you are using email client (i.e. laptop) and (yet) cannot send email through server

server - where smpt is running

On local generate key:
sudo ssh-keygen -t dsa -f /root/.ssh/specialkey
add its public part to ~/.ssh/authorized_keys2 on server

Edit authorized_keys2 on the server and modify line with key to start like
command="netcat localhost 25",no-X11-forwarding,no-agent-forwarding,no-port-forwarding ssh-dss AAAAB3NzaC1k..

Test connection (you should get something about 220 ESMTP Postfix):
sudo ssh login@smtp.server -p ssh_port -i /root/.ssh/specialkey

Add smtp role to /etc/inetd.conf and restart it (on local)
127.0.0.1:smtp stream tcp nowait root /usr/bin/ssh -T -i /root/.ssh/specialkey login@smtp.server -p ssh_port

sudo /etc/init.d/openbsd-inetd restart

Update settings of your mail client on local to use "local" smtp server
localhost:25