InboxGuards is read-only alerting for Microsoft 365 and Google Workspace. It flags new-device logins, forwarding and inbox rules, admin role grants, impossible travel and bulk exports. The page calls it an alarm, not a staffed SOC, and notes that Gmail user filters are not covered by Google audit records, so those need a manual review.
Pricing is $2 per user per month or $20 per user per year, with a 30-day money-back guarantee and no setup fee. Optional hands-on remediation is $199 flat. There is no free monitoring tier; the free items are a first coverage check at setup, a public-DNS spoof check, a sample demo and a scam simulator. It installs from Google Workspace Marketplace or Microsoft AppSource, with optional Slack alerts.
InboxGuards was built after a real mailbox takeover showed up as unexplained forwarding to a random Gmail address, and the builder wanted monitoring of rules, forwards and sign-ins without another heavy security suite.