If James is unable to send email directly due to firewall restrictions, or mail being rejected from the application servers IP address, you may have to configure it to use a gateway mail server to send outgoing messages through.
To do this, you will need to add the following to the <mailet match="All" class="?RemoteDelivery"> directive in the james config file at /usr/local/sourceforge/james/james-<version>/apps/james/SAR-INF/config.xml:
<gateway>smtp.example.com</gateway> <gatewayPort>25</gatewayPort>
You should find these commented out on line 362 of the config file. If your gateway mail server requires authentication to send email, you may also add the following directives:
<username>username</username> <password>password</password>