What it is
SMTP·IMAP·POP3 and their secure variants (SMTPS·IMAPS).
Why it is risky
Cleartext ports (25/110/143) risk credential theft and open-relay abuse (spam laundering).
What to do
Use STARTTLS / encrypted ports (465/993/995) and restrict relaying to authenticated users.
Is it listening on your server?
Linux
ss -ltnp 'sport = :25'Track these versions on your own servers
InfraGuard collects installed software versions from every server and flags the ones with known vulnerabilities. Self-hosted — nothing leaves your network.