email deliverability

ListDefender

Marketing

ListDefender is an email deliverability platform for small businesses. It cleans lists, blocks fake signups, and flags disengaged contacts to help protect sender reputation and reduce bounces.

smtp-probe

Developer Tools

smtp-probe is an open-source email deliverability diagnostic tool that checks SPF, DKIM, and DMARC, verifies addresses through SMTP, and scans IPs against 29 RBL blacklists.