Robert Schetterer Ralf Hildebrandt Patrick Ben Koetter Christian Rößner

Secure and reliable messaging connects people

sys4 specifies and builds turn-key mail systems for high performance. From SMTP boundary filters to mail servers to outbound clusters optimized for deliverability.

The core team for messaging solutions includes Ralf Hildebrandt and Patrick Ben Koetter, authors of "The Book of Postfix: State-Of-The-Art Message-Transport", a global bestseller and the leading reference publication in its field. Remote support including diagnostics and solution development is their daily business.

Dovecot Solutions Oy, Finland, are main technology partners. sys4 is able to implement the industry benchmark open source POP/IMAP server "Dovecot" in extremely challenging environments. Migration from legacy systems to service-based state-of-the-art email platforms is a particular strength of sys4. The practical experience gained is fed back into Dovecot's development pipeline.

The open source project automx is a typical example for sys4's approach to designing email systems with superior efficiency, security and usability. With automx, creating and managing email accounts becomes a breeze.

Contact Us

sys4 AG
Schleißheimer Straße 26/MG
80333 München
+49 89 3090 4664
Contact Persons
Patrick Koetter


Patrick Koetter +49 89 3090 4664

Marc Schiffbauer


Marc Schiffbauer +49 40 6094 5854

Axel von der Ohe


Axel von der Ohe +49 30 6098 4640

Our Thinking

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Real Time Performance Monitoring

by Michael Schwartzkopff on 12/22/2015

Every administrator should know the performance of the servers and services he is responsible for. Normally the performance of services ...

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Postfix Gateway with blind carbon copy Multiplicator

by Robert Schetterer on 05/04/2015

Here is an exotic postfix gateway feature I did. It shows how to setup bcc copy with multiple recipients.

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Cyrus SASL saslauthd man page

by Patrick Koetter on 01/07/2015

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sys4 AG
Schleißheimer Straße 26/MG
80333 Munich
+49 89 3090 4664
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