Zimbra runs webmail, directory, MTA, mailbox, and admin services. Harden network exposure, admin separation, and mail-relay policy before production rollout.
¶ 1) Restrict service exposure and admin interfaces
- Expose only required public mail/web ports.
- Keep admin console and management endpoints off public internet.
- Terminate TLS with strong certificates and modern ciphers.
- Limit SSH/admin access to trusted operator networks.
¶ 2) Harden authentication and policy controls
- Enforce MFA/strong password policy for admin and user accounts.
- Disable unused auth mechanisms and legacy protocols where possible.
- Restrict delegated admin roles with least privilege.
- Rotate service and API credentials during regular maintenance.
¶ 3) Secure mail pipeline and data lifecycle
- Verify Postfix relay restrictions to prevent open relay behavior.
- Keep anti-spam/anti-malware services active and updated.
- Encrypt backups containing mailbox and directory data.
- Monitor Zimbra logs for auth abuse, queue anomalies, and admin changes.
- Zimbra documentation and wiki: https://wiki.zimbra.com/
- Zimbra source repositories: https://github.com/Zimbra
Any questions?
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