Both vendors are based in Germany and run their services in European data centres. The difference is the cut: Retarus grew as a messaging platform for large enterprises and covers fax, SMS and EDI alongside email. Conbool is a suite for mid-sized companies where protection, encryption, archiving and signatures come from one interface. This page sets out which cut suits which setup.
In short
Retarus is the right choice when email is only one of several channels and fax, SMS or EDI should run on the same platform, when several international sites with their own requirements need serving, and when an in-house IT team accompanies the rollout. Conbool is the right choice when email is the channel in question, and when protection, encryption, archiving and central signatures should not turn into four products with four contracts and four interfaces. The practical difference shows less in individual features than in rollout effort: a platform for many channels brings configuration depth that mid-sized companies rarely need but still have to understand and maintain.
No scoring system, because the answers depend on your operation rather than on an overall grade.
Email only, but in full breadth: filtering, encryption, archiving, signatures and continuity. Fax and EDI are not part of the offering.
Fax, SMS and EDI alongside email on the same platform. For organisations that need those channels for regulatory or customer reasons, that is a real argument.
Source: retarus.com, product overview, retrieved September 2026.
Setup through a guided assistant, MX switch and rule set in the same interface. The aim is that one IT person without specialist knowledge can put the system into operation.
Rollout typically accompanied by the vendor and your own IT, with corresponding coordination on interfaces and special cases.
Source: retarus.com, service and onboarding information, retrieved September 2026.
One contract, one tenant, one interface for every module. Licensing is per mailbox, regardless of how many modules are active.
The services are bookable individually and combined according to the setup.
Source: retarus.com, product and service structure, retrieved September 2026.
Operated in German data centres, optionally as an on-premises installation where data must not leave the company.
Operated in the vendor's own data centres, with locations in Germany and further regions for internationally active customers.
Source: retarus.com, data centre information, retrieved September 2026.
Continuity keeps accepting incoming mail and provides a replacement mailbox that can be read and answered from during the outage.
Incoming messages are spooled within the platform and delivered once service is restored.
Source: retarus.com, continuity information, retrieved September 2026.
Switching
The switch happens without interrupting mail flow, because both systems run side by side for a while.
Which services are active today, which rules and exceptions exist, which domains and mailboxes are affected. That list determines what is carried over and what is dropped.
Create the tenant, verify domains, transfer the rule set and exceptions. The MX record stays untouched at this stage, no production mail flows yet.
A test domain or a subset of mailboxes runs through Conbool while the rest stays unchanged. Real traffic shows whether rules and exceptions hold.
The switch is done domain by domain. During DNS propagation both paths accept mail, so nothing is lost.
Only cancel once no traffic has taken the old path for several days. Archived data is secured beforehand.
Retention of archived messages is the point most often overlooked during a switch. Clarify the export format before you cancel.
Decision guide
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Learn moreMore comparisons
Companies evaluating Retarus usually look at these vendors too.
A demo on real mail traffic says more than any comparison table.
Information about the competitor comes from the vendor's publicly available product and service pages. It describes the scope of the offerings, not their quality. Feature sets change; check the current state with the vendor before deciding.
Last updated: September 2026
Retarus is a trademark of Retarus GmbH. It is named here solely to describe the comparison.