Opterius Mail
What Opterius Mail is
Opterius Mail is a free, open-source webmail client presented as a Roundcube replacement for mail servers. It authenticates directly with IMAP and supports SMTP systems including Dovecot, Postfix, Exchange, Zimbra, and Courier. Users can compose, reply, forward, use CC/BCC and inline signatures, save drafts, manage IMAP folders, and search subjects, senders, and message bodies across folders. A per-user address book supplies contact suggestions while composing. Admin mode manages domains, accounts, aliases, distribution groups, quotas, suspension, and autoresponders. The panel checks MX, SPF, DMARC, and DKIM records and can generate RSA DKIM keys and DNS TXT records. Opterius Panel integration provides signed single sign-on and account synchronization. HTML mail is rendered in a sandboxed iframe, while IMAP credentials stay in an encrypted session. The responsive web interface needs no separate mobile app. Installation supports listed Ubuntu, Debian, AlmaLinux, and Rocky Linux versions.
Who it suits
Opterius Mail suits hosting companies, infrastructure teams, and users running compatible IMAP/SMTP systems. It fits deployments wanting webmail plus optional mail administration under open-source licensing.
What it does well
- Free forever under AGPL-3.0
- Supports major IMAP and SMTP servers
- Webmail and administration modes
- DKIM, SPF, DMARC, and MX checks
- Responsive interface without separate app
What to know first
- Requires self-hosted deployment
- Installation supports only listed Linux versions
- Designed around existing mail-server infrastructure
- Administration features require admin mode
Plans
| Plan | Billed and limits | Price |
|---|---|---|
| Free | Free forever · Open-source AGPL-3.0 software · Webmail and administration features included | Free |
| Opterius Mail | Free forever · All features included · open source under AGPL-3.0 | Free |
As opterius.com lists them, read 19 Sept 2026. The maker's own page has the final word.
Verdict
Opterius Mail combines a full webmail client with optional server administration and hosting-panel integration. Its self-hosted nature and operating-system requirements matter for deployment planning.
Facts from Opterius Mail's own pages
- App coverage
- web · opterius.com, 19 Sept 2026
- Compose
- Compose supports reply, forward, CC/BCC, inline signatures, drafts, and contact autocomplete. · opterius.com, 12 Oct 2026
- Contacts
- It includes a per-user address book that suggests saved contacts while composing messages. · opterius.com, 12 Oct 2026
- Deployment modes
- It can run as webmail for existing IMAP/SMTP infrastructure or in admin mode with mail server management features. · opterius.com, 12 Oct 2026
- DNS and DKIM
- The admin panel checks MX, SPF, DMARC, and DKIM records and can generate per-domain RSA DKIM key pairs and DNS TXT records. · opterius.com, 12 Oct 2026
- Documentation and support
- The maker's documentation lists Opterius Mail setup, configuration, SSO integration, plugins, and administration guidance. · opterius.com, 12 Oct 2026
- Folders and search
- Users can create, rename, and delete IMAP folders, and search subjects, senders, and message bodies across folders using IMAP UID SEARCH. · opterius.com, 12 Oct 2026
- Free plan
- Yes · opterius.com, 19 Sept 2026
- Headquarters
- Romania · opterius.com, 28 Sept 2026
- Installation and supported systems
- The installer configures Dovecot and Postfix integration and supports Ubuntu 22.04/24.04, Debian 11/12, AlmaLinux 8/9, and Rocky Linux 8/9. · opterius.com, 12 Oct 2026
- Intended users
- The maker describes Opterius as a hosting control panel built for hosting companies and describes Mail as a platform for users and infrastructure teams. · opterius.com, 12 Oct 2026
- Mail administration
- Admin mode supports mail domains, accounts, aliases, distribution groups, per-account quotas, account suspension, and autoresponders. · opterius.com, 12 Oct 2026
- Mail protocols
- It authenticates directly against IMAP and supports SMTP mail servers, including Dovecot, Postfix, Exchange, Zimbra, and Courier. · opterius.com, 12 Oct 2026
- Mobile use
- The web interface is mobile-responsive and the product page says no separate mobile app is required. · opterius.com, 12 Oct 2026
- Panel integration
- Opterius Panel integration provides HMAC-SHA256 signed single sign-on, and the product page says Mail ships as Panel's default webmail with automatic account sync. · opterius.com, 12 Oct 2026
- Purpose
- Opterius Mail is an open-source webmail client described as a Roundcube replacement for a mail server. · opterius.com, 12 Oct 2026
- Security
- The product page says HTML email is rendered in a sandboxed iframe and IMAP credentials are kept in an encrypted session rather than written to the database. · opterius.com, 12 Oct 2026
Where Opterius Mail stands on Freedom251
- Email clients#90 of 142