You can configure the timeout script on your source node, to have a qie.error() in order to get an email if there is a timeout.
For an FTP source:
You can set the Channel Properties to alert you on every send or receive error:
The default is to alert every 10 errors. You can configure this so you get an email on every error. Also checking the "Alert on first error" will ensure you get emailed if it cannot connect to the FTP server.