If you are receiving any of the following messages:
Send Message Error
Sending of message failed.
An error occurred sending mail: SMTP server xxx.com is unknown. The server may be incorrectly configured. Please verify that your SMTP server settings are correct and try again.Send Message Error
Sending of message failed.
The message could not be sent because the connection to SMTP server xxxx.com timed out. Try again or contact your network administrator. Additionally, verify that your firewall or antivirus program is not preventing Postbox from sending email.
... then you could have a problem connecting to your network. Try accessing the Web using a browser, and if that doesn't work, try connecting to a different network or troubleshooting the network that you are on.