Hi, you can absolutely use your Cruzio mail while travelling, but our outgoing server needs to authenticate you as a legitimate user first.
Cruzio uses an authentication method known as "pop before smtp" basically as long as you connect to our server to check mail (popping) before you send email you'll be able to send without a problem.
Some email programs have an option to check mail before sending, in some it's even explicitly labelled as "pop before smtp" but even without this setting if you can manually check mail before trying to send you shouldn't have any trouble.
One other potential problem is that many ISP's block access to off-network smtp mailservers on port 25, you may also need to configure your mail program to use port 587 instead of port 25. In most mail programs this is found under the advanced settings for your outgoing mailserver.
Instructions for changing the outgoing mail port for windows email clients are here http://www.cruzio.com/index.php?option=com_smf&Itemid=38&topic=294.msg869#msg869
Instructions for changing the outgoing mail port for Mac email clients are here http://www.cruzio.com/index.php?option=com_smf&Itemid=38&topic=293.msg868#msg868