mailfloss has a good set of defaults in terms of what it cleans and does not clean. However, if you are looking for more find grained controls then you can go ahead and add your blacklist and whitelist options here. Remember to click on the link “Toggle whitelist/blacklist” as they are hidden by default.
Blacklist options are for keywords you don’t want in the email addresses, such as swear words. Whitelist options are for keywords you do not want filtered. These could be specific role-based email addresses such as “administrator” or “info” or “mailflossIsRulez”.
If you know what you want to add to your blacklists or whitelists, go ahead and do so now. Otherwise, you don’t have to do anything and mailfloss will take care of the heavy lifting/flossing for you.