When installing the Inbound and outbound Mail services a password was specified - if you change the password within Console say, though it doesn't update these files - and with the passwords being encrypted you're not able to edit the files.
Run the Touchpaper Password Configuration Tool (available in the TPS Virtual Directory) and specify the following: Username, Password, Servername and Virtual Directory. Tick the applications that you want the config files to be updated for. Then click "Go" and this will update the files with the encrypted password
** Please note from 7.5 this the account can be updated in the Configuration Centre. The above is relevent to the tray applications used for troubleshooting **