Bouncer is a great tool that enables you to check whether an email address is deliverable. Often email/contact finders provide email addresses that are not valid. This decreases your deliverability rate and if you send out emails too often to email addresses that bounce you will be flagged by Outlook/Gmail as spam and your emails will end up in... well someone’s spam folder :(.
Always use Bouncer if you are sending out email campaigns and only send out emails to addresses that have been verified by Bouncer.
Bouncer