Retarus and Conbool compared.
On filtering, encryption, archiving and continuity the two cover the same ground. The difference lies in signatures, DMARC, backup and awareness, and in the question of who may run the platform.
Where the two meet, and where they do not.
Nine modules, one platform, one contract. Retarus covers four of them according to its public portfolio, five it does not.
- MailGuardspam, phishing, BEC
- SecureMailS/MIME, OpenPGP, portal
- SecureFileslarge attachments
- Disclaimersignatures centrally
- DMARC Reportsoutbound identity
- Archiveaudit-proof, WORM
- 365 Backupback up Microsoft 365
- Awarenessphishing simulation
- Continuitymail flow during an outage
Classification follows the portfolio published on retarus.com, home page and email security section, retrieved in September 2026. Listed there are Secure Email Gateway, Advanced Threat Protection, Sandboxing, Post-Delivery Protection, Email Continuity, Email Encryption, Email Archive and Policy Engine. What your contract covers is settled by the quote.
Verifiable
Eight points that make the difference.
Every point is described in our public documentation and can be checked in a demo.
Signatures and legal footers centrally
One template per tenant, applied server side, with campaign banners and measurement. Also available as an add-in without touching the mail flow.
DocumentationEvaluating DMARC, not just sending it
Reports are collected, evaluated and translated into steps until your own domain sits at reject.
DocumentationBack up Microsoft 365 and restore it
Mailboxes, calendars and files on a fixed schedule, plus users and groups from Entra ID. Restorability is tested and documented once a year.
DocumentationAwareness built on real incidents
Phishing simulation and training from the same interface, using defused attacks from your own traffic rather than a library.
DocumentationLarge attachments without a detour
Anything too large for the mail flow goes out as a retrieval link with an expiry and a log. For the sender it stays an attachment in Outlook.
DocumentationRunning it in your own data centre
The same platform on premises when no message may leave the building. Updated at the push of a button, with no call home to the cloud.
DocumentationTenants from one account
Partners and system houses manage every customer from one interface, distribute licences from a pool and hand rule sets on as a sealed package.
DocumentationSIEM export as a stream
Events go to Splunk, Microsoft Sentinel and QRadar, in CEF, LEEF, ECS or JSON. The audit log is the same for every module.
DocumentationPath to the recipient
How the message arrives.
Here the two are close together. For encryption Retarus names S/MIME, PGP and OpenPGP as well as a secure web mailer for recipients without a solution of their own. Conbool takes the same route.
Conbool
- Recipient with a certificate or key: encryption with S/MIME or OpenPGP, opened in the familiar client.
- Recipient with neither: an invitation to the reader portal, replies possible, no account needed.
- Optionally as an encrypted PDF that opens on any device.
Retarus
- By its own description S/MIME, PGP and OpenPGP, including your own certificates to X.509 v3.
- A secure web mailer is available for partners without a solution of their own.
- Keys and certificates are, by its own statement, created, distributed and managed for you.
Details from retarus.com, Email Encryption page, retrieved in September 2026. On encryption itself we see no defensible difference we could claim.
Operations
Where messages are processed.
Retarus describes the service as a cloud service, connected through the MX record or a connector, with processing in the EU. An installation in the customer's data centre is not stated on the public pages. At Conbool the deployment model is a property of the tenant.
Cloud in Germany
Operated in German data centres, a German company as your contracting party, processing under Article 28 GDPR.
Your own outbound path
Partners and system houses send from their own IP without leaving the shared administration.
In your own data centre
A complete installation on your premises when no message may leave the building. Same interface, same rules.
In operation
Six points from everyday use.
What matters in operation is documented and can be followed in a demo.
Outbound messages
Rules per recipient domain, attachment type and size decide whether a message is signed, encrypted or placed in the portal.
DocumentationInbound messages
Decryption and signature checking at the gateway, so the filter sees the plain text instead of stopping at the encryption.
DocumentationMicrosoft 365
Connected through a connector, or as an add-in without touching the mail flow where no connector may be set.
DocumentationThunderbird and other clients
A dedicated Thunderbird add-on, plus the gateway route for any client that speaks SMTP.
DocumentationArchive and search
Full-text search across the archive, export for auditors, retention per tenant.
DocumentationRunning it yourself
The same platform on premises, updated at the push of a button and with no call home to the cloud.
DocumentationOur view
When Conbool is the right choice.
- If you need signatures, DMARC, backup and awareness from the same interface alongside filtering and encryption.
- If you want to choose the deployment model yourself, from cloud to an installation in your own data centre.
- If you are a system house managing several customers and handing rule sets on as a sealed package.
- If you are a mid-sized organisation looking for one contact without an intermediary.
- If you want to send large attachments through the same vendor instead of a second service.
In fairness
When Retarus is the right choice.
- If you need fax, SMS and EDI alongside email from one source: we offer none of those.
- If a sandbox with its own analysis chain is a stated requirement.
- If you are an enterprise connecting globally distributed sites to a single service.
- If you want an archive with long retention in the same contract and need no further modules.
What prospects ask us about this.
Where these statements come from.
Statements about Retarus rely exclusively on publicly available sources: retarus.com, namely the home page with its product structure, the email security section and the Email Encryption page. We make no claims about internal processes or architecture that are not publicly documented. Where a source is silent, the table says not stated rather than no. Statements about Conbool rely on our own documentation and on contractual commitments. As of September 2026. Products change, so we recommend asking both vendors directly about the points that matter to you and taking the answers in writing.
See both in a demo.
We show filtering, encryption, archiving and continuity using an example from your industry, along with the disciplines beside them.