grommunio User Guide

grommunio GmbH

2026-07-02

grommunio User Guide

Welcome! This guide helps you use grommunio every day — mail, calendar, contacts, tasks and notes, chat, video meetings and file sharing — whether you work in the browser, the desktop app, or your own e-mail client. grommunio is built on familiar, standards-based protocols, so no special training is needed.

Where to start

grommunio WebThe full-featured web interface — nothing to install, just a modern browser. The recommended way to use every feature.

grommunio DeskThe native desktop app for Windows, macOS and Linux, with tray integration and OS notifications.

Connecting other clientsSet up your account in Outlook, Apple Mail, Thunderbird or on your phone.

TroubleshootingFixes for the issues users hit most often — sign-in, sync and more.

New here? Start with the Introduction for an orientation, or jump straight into the grommunio Web chapters.

Offline reading

This section is also available to download for offline use:

Download as PDF

Download as EPUB

Introduction

This manual helps you work with grommunio every day — reading and sending mail, keeping your calendar, managing contacts, tasks and notes, chatting and meeting, and sharing files. grommunio is built on well-established, standards-based protocols, so if you already know an e-mail client, you will feel at home quickly; no special training is required.

Ways to access grommunio

grommunio is a complete communication and collaboration suite — e-mail, calendaring, contacts, tasks, notes, video meetings, chat and file management. You can reach it in three ways, and you can mix them freely on the same account:

grommunio WebThe full-featured web interface — nothing to install, just a modern browser. The recommended way to use every grommunio feature.

grommunio DeskA native desktop app for Windows, macOS and Linux with tray integration and OS notifications.

Outlook & other clientsConnect Microsoft Outlook, Apple Mail, Thunderbird or your phone using native protocols.

Because grommunio speaks the standard protocols (Exchange/MAPI, Exchange ActiveSync, IMAP/SMTP, CalDAV/CardDAV), most clients work with it. Not every client exposes every grommunio feature, though — grommunio Web brings all of them together in one place, which is why it is the recommended starting point.

Using this manual

The grommunio Web chapters are the heart of this manual: a feature-by-feature guide to the web interface.

grommunio Desk covers the native desktop application.

Connecting other clients shows how to set up your account in Outlook, Apple Mail, Thunderbird and on mobile devices.

Troubleshooting collects fixes for the issues users hit most often.

Screenshots are provided for illustration; the exact appearance may differ slightly between versions and platforms, but the steps remain the same.

Note

This documentation does not replace the vendor documentation of third-party clients (such as Microsoft Outlook or Mozilla Thunderbird). For clients that are not exclusive to grommunio, also refer to the documentation provided by the client's vendor.

Found a difference, or stuck?

If something in your environment does not match, or you cannot set up your account, we welcome questions and corrections in the community at https://community.grommunio.com, or — with a valid subscription — at office@grommunio.com.

grommunio Desk

grommunio Desk is the native desktop client for grommunio, available for Windows, macOS and Linux. It gives you grommunio Web in a dedicated application window — with desktop integration that a browser tab cannot offer: system-tray background operation, OS-native notifications, and the ability to manage several grommunio servers from one place.

Same features as grommunio Web

The desktop client renders the full grommunio Web interface, so everything in the grommunio Web guide — Mail, Calendar, Contacts, Chat, Meet and the rest — applies inside grommunio Desk as well. This page covers only what is specific to the desktop application.

Installing

Download the installer for your platform from the grommunio download portal and run it:

grommunio.com/download

Builds are available for Windows, macOS and Linux. After installation, launch grommunio Desk like any other application.

First start — adding a server

On first launch, grommunio Desk shows a start page where you connect to your grommunio server:

Choose Add server (also available later from the Server menu).

Enter the URL of your grommunio server, for example https://mail.example.com. The address is validated before it is saved.

Confirm. grommunio Desk loads the grommunio Web login for that server; sign in with your e-mail address and password.

Your server and session are stored locally, so the next start takes you straight back in.

Working with multiple servers

grommunio Desk can hold several server profiles at once — useful if you access more than one grommunio environment (for example a work and a private mailbox, or several customer systems):

Add additional servers from the Server menu via Add server.

Switch between connected servers from the title bar / Server menu.

Remove a server you no longer need from the Server menu (you are asked to confirm).

Application menus

The menu bar provides the usual desktop actions:

Menu | Contents
File | Application-level actions and quitting grommunio Desk.
Server | Add, switch and remove server profiles; return to the start page.
View | Reload and zoom the current view.
Help | Product and version information.

Background operation & the tray icon

grommunio Desk keeps running in the background so you continue to receive notifications after closing the window:

Closing the window minimises the application to the system tray rather than quitting it.

Use the tray icon's Open App entry to bring the window back to the front.

To exit completely, quit from the File menu (or the tray menu).

Notifications

grommunio Desk raises OS-native notifications (Windows, macOS and Linux) for new mail and other events, so they appear in your operating system's normal notification area even when the window is in the background. Make sure notifications are allowed for grommunio Desk in your operating system settings.

Default mail handler (mailto links)

grommunio Desk can act as your system's handler for mailto: links. When you click an e-mail address in another application, grommunio Desk opens a new message — asking which connected server to send from if you have more than one.

Configuration & log files

Application data is stored per user in the OS configuration directory:

Platform | Configuration | Logs
Linux | ~/.config/grommunio Desk/config.json | ~/.config/grommunio Desk/logs/
macOS | ~/Library/Application Support/grommunio Desk/config.json | ~/Library/Application Support/grommunio Desk/logs/
Windows | %APPDATA%\grommunio Desk\config.json | %APPDATA%\grommunio Desk\logs\

File logging is off by default and can be enabled in the configuration when diagnosing a problem; when enabled, a main.log and a renderer.log are written to the logs directory above.

Note

grommunio Desk is open-source (AGPL-3.0). Source code and issue tracking live at github.com/grommunio/grommunio-desk.

Connecting Outlook & other clients

Besides grommunio Web and grommunio Desk, you can connect your grommunio account to a client you already use. grommunio speaks the native protocols — Exchange/MAPI for Outlook, Exchange ActiveSync (EAS) for mobile devices, and IMAP/SMTP with CalDAV/CardDAV for clients such as Thunderbird — so setup is usually a matter of entering your e-mail address and password.

Note

Not every client exposes every grommunio feature. For the complete feature set, use grommunio Web.

Microsoft Outlook

grommunio accounts can be configured for Microsoft Outlook, as grommunio natively supports the protocols used by Microsoft Outlook (RPC-over-HTTP and MAPI-HTTP).

In this configuration setup, it is assumed no profiles have been set up so far. If MAPI profiles already exist on the system, new profiles and accounts can be added by executing outlook /profiles.

Select a name for the new profile and confirm.

In the following dialog, the Outlook profile assistant will request your email address. It is recommended to check "Let me set up my account manually", to ensure the correct protocol is chosen, as some Outlook versions otherwise choose a non-native protocol like IMAP, which would incur feature limitations.

The account type / protocol choice dialog. For grommunio, select "Exchange".

The following progress dialog might take a few seconds, since Outlook is now attempting to contact the mailbox for the first time and populate the Outlook profile. In that process, it will ask for credentials. Select "Remember my credentials" to save the password for this user identity in the Windows system. Anytime Outlook requests access to the mailbox it can do so without prompting again.

As part of the manual setup, the wizard will display another page with Offline Settings. You can switch between Online Mode and Cached/Offline mode here. When offline mode is enabled, Outlook keeps a copy of the mailbox locally and uses forth-and-back synchronization. A slider is shown to specify the timeframe of messages to synchronize. Older versions of Outlook allow choosing from a handful of options for the timeframe, e.g. 1 day, 1 week, 2 weeks, ... 3 months and "All". Contemporary version of Outlook (circa 2019 and onwards) are somehow defective, and the slider is greyed out, leaving only full synchronization for the offline mode.

The profile has now been set up and ready for use.

Note

By default, the account setup will show "Microsoft Exchange" account type. The setup procedure of Microsoft Outlook with grommunio Groupware does not differ from a setup with Microsoft Exchange. As with Microsoft Exchange, the default profile is set up for Offline/Cached Mode, which synchronizes the mailbox for offline usage. grommunio Groupware supports Offline/Cached Mode. However, this might not be preferred in some use cases and should be disabled, e.g. with most Remote Desktop Server environments.

Caution

For the groupware features of grommunio, no separate software needs to be installed. However, the exact Microsoft Outlook setup procedure might differ from what is depicted above, depending on the version used. When setting up the Outlook account with grommunio Groupware in use, proceed with the client installation as if it were to be configured with Microsoft Exchange. For automation purposes, third-party software may be used for account and profile creation, so long as the compatibility of the third party software includes Microsoft Exchange.

Android

grommunio Accounts can be easily added to Android devices, as they natively support the Microsoft Exchange ActiveSync (EAS) protocol.

To add your grommunio account to your Android device, navigate to Settings -> Accounts page, and select Exchange

In the following setup dialog, enter your email address, select Next

In the following setup dialog, enter your password, select Next

After finishing the account setup your data is being synchronized in the background.

Depending on the grommunio backend configuration, you might be requested to accept a corporate policy setting to finish and accept the configuration. Note that this (depending on your configuration) might allow system administrators (and yourself through grommunio web) to setup specific policies or handle the device through mobile device management. The rights you are to be granting by this so-called provisioning step are shown in the subsequent dialog. The possibilities of profile settings vary from Android versions and OEM configurations (brand of mobile device).

After having setup the device, your new account will show up at Settings -> Accounts, with the possibility to setup more configuration options with your profile (such as signatures, synchronization periods, and more). The possibilities of configuration settings vary by Android versions and OEM configurations (brand of mobile device).

With the configuration of your mobile device with an exchange account, your mobile device has access to the data of your account through the personal information manager (PIM) interface. This allows you to use your grommunio mailbox with a variety of applications of your choice, such as a mail or calendar application of your preference.

Apple iOS

grommunio Accounts can be easily added to iOS devices (such as iPhone or iPad), as they natively support the Microsoft Exchange ActiveSync (EAS) protocol.

To add your grommunio account to your iOS device, navigate to Settings page, and select Mail

In the Mail settings, select Add Account

In the following setup dialog, select Microsoft Exchange as account type

In the following setup dialog, enter your email address, choose an account description, and select Next

After confirming your account information, you will be requested whether you want to sign-in by using Microsoft, or manually want to configure your account information. Since grommunio is equipped with AutoDiscover technology, both possibilities are available.

With the following dialog, your credentials (which you are requested to enter) could be verified correctly, and you can select which information should be synchronized with your iOS device, namely Mail, Contacts, Calendar, Reminders and Notes. After hitting Save your account setup has finished and your data is being synchronized in the background.

After finishing the account setup your data is being synchronized in the background.

Depending on the grommunio backend configuration, you might be requested to accept a corporate policy setting to finish and accept the configuration. Note that this (depending on your configuration) might allow system administrators (and yourself through grommunio web) to setup specific policies or handle the device through mobile device management. The possibilities of profile settings vary by different iOS versions.

With the configuration of your mobile device with an exchange account, your mobile device has access to the data of your account through the personal information manager (PIM) interface. This allows you to use your grommunio mailbox with a variety of applications of your choice, such as a mail or calendar application of your preference.

Microsoft Mail

grommunio Accounts can be easily added to Microsoft Mail, as grommunio natively supports the protocols used by Microsoft Mail.

To add your grommunio account to Microsoft Mail, open Microsoft Mail and select Accounts in the left menu and after that Add account on the account management pane on the right side.

In the following dialog the Microsoft Mail account assistant select Office 365 account type from the list.

The following dialog requests the entry of the email address, which should be entered here, select Next to continue.

After a few seconds, the next dialog requests the password of the account, select Logon after entry.

After entering the credentials, Microsoft Mail will automatically (based on AutoDiscover technology) detect your settings after a few seconds.

After completed setup of the account, Microsoft Mail will confirm the successful account creation and synchronize all information with your Microsoft Windows device.

Note

Microsoft Mail will automatically store the credentials without the option to deselect this feature. The password hereby is stored in the Microsoft Windows user profile used for the account creation.

Caution

With the account creation in Microsoft Mail, the Windows default Apps People and Calendar automatically have access to the same account information and automatically synchronize your grommunio account with the Microsoft Windows device.

Mozilla Thunderbird

Mozilla is a free and open-source cross-platform email and personal information manager. grommunio fully supports Mozilla Thunderbird with its primary protocols, IMAP(s), POP3(s), SMTP(s) as well as CalDAV(s). Additionally, with full support for CardDAV(s) by grommunio, the official Mozilla Thunderbird plugin named "CardBook" can be used for synchronization of contacts.

Thunderbird: E-Mail

To setup an email account with Mozilla Thunderbird, choose File -> New -> Existing Mail Account... and fill in your personal mail account settings:

If you want your authentication information to be stored on your system, use the Remember password option, so it will not prompt you the next times you open Mozilla Thunderbird.

Press Continue when you have your confirmed your information to be correct.

The summary page will provide you with the functionality available for Mozilla Thunderbird. During configuration, the warning Configuration found, but no addons known to handle the config might show up. You can safely ignore this hint, since Mozilla Thunderbird does not understand all protocols available by grommunio, which is the reason for this warning to show up. Mozilla Thunderbird automatically detects the correct mail server information for you and sets the protocol encryption for you. With the choice of your favorite protocol, select Done and your account is setup.

Thunderbird: Calendar

To setup a calendar account with Mozilla Thunderbird, choose File -> New -> Calendar... and select On the Network as the location of your calendar.

In the upcoming dialog choose CalDAV as Format, enter your Username and set the location appropriately. Per default, your personal Calendar is reachable under "https://<Server URL>/dav/calendars/<Username>/<Calendar Name>". If you do not have this information, contact your administrator to provide you with this information accordingly. In most cases, the server URL matches your grommunio Web URL. Checking the checkbox Offline Support will make sure you can access your calendar information also without an active connection to your provider.

Note

Since grommunio support multiple calendars in a Mailbox, the <Calendar Name> is needed to be specified explicitly. Note that this URL is sensitive to correct spelling, which means a users mailbox' calendar is most likely to be named Kalender in german, for example.

The next dialog in the CalDAV account setup will give you options to setup your Calendar account, such as giving it a specific name, color and activate reminders. It is recommended to choose the corresponding email account correctly - This ensures appointment handling is matching the correct calendar/mailbox pairing.

As final dialog you will be presented to provide your credentials to be able to access your calendar. You can identify being connected to the correct server URL by seeing the prompt: The site says: "grommunio dav". Use the same credentials as with your email account to access your calendar information.

Thunderbird: Contacts

To setup a contacts account with Mozilla Thunderbird, it is first required to install a plugin with Mozilla Thunderbird. The well-known plugin "CardBook" is fully tested and supported with grommunio, and available at the following location: https://addons.thunderbird.net/de/thunderbird/addon/cardbook/. Download the plugin and install it, to make your Mozilla Thunderbird installation to support contacts management based on the vCARD standard. To install it, you need to download and install the plugin (an XPI archive) or download it directly within Mozilla Thunderbird via File -> Add-Ons and search for the Add-on CardBook and select Add to Thunderbird. It will be automatically installed and with installation it will request you for the necessary permissions, which need to be accepted for proper operation of the plugin.

After installation, choose the CardBook Tab from Mozilla Thunderbird, and within CardBook, choose Addressbook -> New Adressbook and select Remote as address book location and select Next >.

For setting up your grommunio Contacts folder, choose CardDAV as your remote address book type. Per default, your personal Calendar is reachable under "https://<Server URL>". In most cases, the server URL matches your grommunio Web URL. After entering your credentials (Username and Password) you can validate your correct configuration with the button Validate.

After successful validation, select Next > to continue your address book configuration.

The final dialog will give you options to setup your address book account, such as giving it a specific name and color. Checking the checkbox Work Offline will make sure you can access your calendar information also without an active connection to your provider.

Troubleshooting

Common problems and how to resolve them yourself. If none of these help, contact your administrator or the grommunio community.

Signing in

If you cannot sign in to grommunio Web:

Double-check that you are using your full e-mail address as the username, and that Caps Lock is off.

Confirm the server address in your browser's address bar matches the one your administrator gave you.

If you recently changed your password, make sure connected apps and mobile devices use the new one.

Still stuck? Your account may be locked or disabled — ask your administrator.

The web interface looks broken or out of date

After an update, the browser may still be using cached files:

Reload the page bypassing the cache: Ctrl+Shift+R (Windows/Linux) or Cmd+Shift+R (macOS).

If problems persist, clear your browser's cache for the grommunio site, or try a private/incognito window to rule out an extension.

Use a current version of a mainstream browser (Edge, Chrome, Firefox or Safari).

A message I expected did not arrive

Check the Junk folder — the message may have been filtered as spam; mark it Not Junk to train the filter and move it back.

Check your message rules (Settings → Rules) in case a rule moved or deleted the message.

Ask the sender whether they received a non-delivery report. If so, share its text with your administrator.

Mobile devices (Exchange ActiveSync)

If synchronization problems with your mobile device persist and a normal resync did not help, reset the device's connection:

Remove the grommunio account from the mobile device.

In grommunio Web, go to Settings → Mobile Devices and remove the device(s).

Wait at least fifteen minutes.

Recreate the account on the mobile device.

This clears the server-side sync state so the device starts a clean synchronization.