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Email Security Management · Mailbox account takeover

Email account takeover checklist for 2026

Short answer

A complete email account takeover checklist has 4 setup items and 2 things to audit against. Work through setup in order, then schedule a quarterly review.

Setup checklist#

  • ☐ Enforce phishing-resistant MFA (FIDO2 keys or passkeys) for admins and finance.
  • ☐ Review third-party OAuth grants monthly and restrict user consent.
  • ☐ Alert on impossible-travel logins and mass downloads.
  • ☐ Have a documented response: revoke sessions, reset, audit rules and forwards, notify affected parties.

Audit checklist#

  • ☐ Confirm you are not: sMS-based MFA for high-value accounts.
  • ☐ Confirm you are not: not checking forwarding rules after remediation.

Ongoing monitoring#

  • ☐ Weekly: review provider dashboards (Postmaster Tools, SNDS) and bounce logs
  • ☐ Monthly: re-run the setup verification after any vendor or DNS change
  • ☐ Quarterly: full audit against this checklist

Frequently asked questions#

What are signs of a compromised email account?

Unknown sent items, new forwarding rules, missing mail, login alerts from unfamiliar locations, and contacts reporting odd messages.

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