This Administrator Manual covers everything regarding installation, operation and maintenance of the grammm software suite. The intended audience for this documentation is rather for administrators and system operators deploying grammm.


grammm delivers a fully-featured communication solution which covers all aspects of the software-defined era. As a modern and modular platform, grammm helps to simplify all needs of modern communication by providing the following feature set:

  • E-Mail

  • Calendar

  • Contacts

  • Tasks

  • Notes

  • Video meetings

  • Chat

Overview & Concepts

grammm is shipped as an integrated software appliance for deployment on target systems by combining an embedded, optimized operating system, based on openSUSE. While grammm is also shipping software repositories for major Linux platforms, the software appliance allows quick deployment on a variety of platforms, including bare metal and virtualized environments.


grammm’s software component stack is modular and consists of the following main components:



Component Group

gromox-delivery, gromox-smtp

Local delivery agent that places messages received from Postfix into mail stores

grammm core service (Gromox)


Software bus inter-process communication (IPC) mechanism that allows communication between multiple processes running concurrently on multiple machines.

grammm core service (Gromox)


The mail store (exmdb), and HTTP interface for RPCH, EWS, and optional FastCGI passthrough

grammm core service (Gromox)


IMAP interface providing industry-leading performance to IMAP clients

grammm core service (Gromox)


POP3 interface

grammm core service (Gromox)


Bridge process between PHP-MAPI and exmdb

grammm core service (Gromox)


Message index database, mostly an acceleration mechanism for use by IMAP

grammm core service (gromox)


A REST interface for automation and which provides the main API for grammm’s administration web interface

grammm Admin


grammm-admin-web is the central administration interface for system-, domain- and user-management

grammm Admin


grammm-antispam not only keeps your mail service clean from spam but also provides interfaces for anti-virus scanning and filtering

grammm Admin


grammm-web is the user’s main web interface delivering a rich user experience to browser-based clients

grammm web service


grammm-sync provides the main EAS (Exchange ActiveSync) service for native clients, such as iOS, Android and other EAS-capable clients

grammm web service


grammm-dav provides the main CardDAV and CalDAV service for native clients, such as macOS and other capable clients

grammm web service

Other software components used in combination with grammm:

  • MariaDB is the central database for all user metadata which provides the main database for all backend services. No user payload data (e-mails, etc.) are stored in this database.

  • Postfix provides world-class functionality and versatility as the de-facto standard MTA which allows even the most complex mail routing setups.

  • nginx is a fast, robust and modern web server acting as the main web server and providing major services via HTTP and RPC to clients.

  • SQlite is used for storage of the individual users’ mailbox stores.