I have setup postfix and hylafax to talk to each other and I can now send
faxes from email with no trouble. I followed the instructions here and all
worked:
http://www.postfix.org/faq.html#fax

To send a fax a user sends an email to:
123456789@fax.ourdomain.com.au

This is fine however it's a bit long winded and would be simpler if it
could be shortened to:
123456789@fax

Would this simply be a case of changing the entry in:
etc/postfix/transport from:
fax.your.domain fax:localhost
to
fax fax:localhost

Thanks