No logs generated during the email validation process

Problem/Motivation

When emails are sent through to the Byteplant Email Validation service, not logging is generated at any time. At minimum it seems to me that the system should log when an email fails validation. Or at least this should be an optional configured value.

Steps to reproduce

Configure the email validation module and then attempt to validate a known junk email.
Note that even though the form returns an error that the email is invalid, no error is actually logged in the system.

Proposed resolution

Add logging options to the module so admins can configure how much logging they prefer to generate.

Remaining tasks

Perform the needed updates to the code to add logging.

User interface changes

New fields will be present the settings page that will allow admins to toggle logging on and off as needed.