Currently mailfloss has 3 floss modes of aggressiveness which determine how aggressive mailfloss will perform email verification. These settings are only for connected email service provider integrations for maximum flexibility. Below is a brief explanation of each.
Remember that there's a "help me decide" link beside the Aggressiveness options that you can click on to help you decide which mode option is the best for your contacts list.
Normal floss (recommended for most users), formally called Medium
maifloss will floss for nonexistent, available, banned, deactivated, inbox_full, and disposable email addresses in addition to the tests in Safe mode. This is a sensible option and recommended for most users.
For more detailed information about Normal aggressiveness, check this article.
Aggressive floss (not recommended)
mailfloss will do a deep clean on your email list. Anything that looks remotely bad will be flossed away. Choose this to maximize email deliverability, but only if you are cool with the consequences. There will likely be more false positives if your email list is new, and less false positives with older lists but they'll almost always be there. We recommend this option only if your list is really old or you want a really deep clean. We do not recommend for most customers Aggressive + Autofloss + Auto-delete or Auto-unsubscribe. This is almost never recommended. Please get in touch with us if you think you need to have your settings like this so we can talk you out of it.
For more detailed information about Aggressive aggressiveness, check this article.
Custom floss
Somewhere between "Safe" and "Aggressive" floss aggressiveness, this allows you to customize everything in-between the two. Hover over the question mark to see an explanation of what each setting means.
For more detailed information about Custom Floss, check this article.