Outbound mail reporting 'Invalid length for a base-64 char array' error

Version 1
    Question

    Outbound mail doesn't poll and within event viewer the following error is captured 'Invalid length for a base-64 char array'  followed by some 'Failed to logon' errors

    Answer

    The error and failed logins are because the password has been manually edited in the config files which should be encrypted (by the installation program.  Uninstall and reinstall the service ensuring the password is entered into the installer.

    Environment

    7.1.3 upwards