RelaySentry

RelaySentry is a web app (with a lightweight Linux agent) that monitors outbound SMTP behavior and blocks abuse in real time. It focuses on the ugly, common problem: compromised accounts or misconfigured apps turning your SMTP relay into a spam cannon, getting your IP/domain listed and killing deliverability. The agent tails mail logs (Postfix/Exim/OpenSMTPD) and streams normalized events to the dashboard. You set guardrails like per-user/per-app rate limits, unusual recipient spikes, geo-impossible logins, and sudden bounce/deferral surges. When thresholds trip, RelaySentry can automatically throttle, quarantine a sender, rotate credentials, or temporarily disable a relay route—then generate a clear incident report for IT and compliance. It also includes a “deliverability hygiene” view: blacklist checks, rDNS/SPF/DKIM/DMARC validation, and alerts when reputation indicators degrade. This is not a full MTA replacement; it’s a safety layer for the SMTP servers you already run.