Account delegation

The Mail app supports account delegation if the delegation is handled by the mail server. That means the mail server has to accept emails sent from an alias address.

In mailcow, for example, the setting is called Also allowed to send as user.


Unless paired with shared Sent mailboxes or handled otherwise by the mail server, sent messages will be stored in the sender’s personal Sent mailbox.

Snooze and scheduled sending


If AJAX is selected for cron job execution in the admin settings, the snooze feature and scheduled sending are deactivated because of unreliable execution.

XOAUTH2 Authentication with Microsoft Azure AD

New in version 3.0.0.

The Mail app supports XOAUTH2 authentication with hosted Microsoft Outlook accounts. An app has to be registered in the Microsoft Azure web interface and its credentials have to be supplied to the Nextcloud instance. You can find relevant settings in the Groupware section of the admin settings.

Step 1: Open the Azure AD Dashboard

Visit the Azure portal and navigate to the Azure AD dashboard.


Step 2: Create a new app registration


Chose a name, allow organizational and personal Microsoft accounts. Configure a web app and copy the redirect URI from the groupware settings of your Nextcloud instance. Have a look at step 8 on where to find the redirect URI. Finally, click on register to proceed.


Step 3: Copy the client ID

This ID will be needed later for the Nextcloud settings.


Step 4: Create a new client secret


Chose a descriptive name for the secret and set the an appropriate expiration date. Click on add to create the secret.


Step 5: Copy the client secret

Copy the client secret manually or by clicking on the copy button. You can find it in the value column. The secret will also be needed later for the Nextcloud settings.


Step 6: Configure Nextcloud

Open the groupware settings in the Nextcloud admin settings and fill in the client ID and client secret. Leave the tenant ID as is (common). You can also find the redirect URI here. Click on save to proceed.


Using a custom tenant ID is not covered by this guide. Only configure it if you are an expert and changed the supported account types in step 2.


Step 7: Connect Microsoft Outlook accounts

Congratulations! You are now able to use hosted Microsoft Outlook accounts in the Mail app. Use your Microsoft account email and any password when adding your account. The password will be discarded and you will be prompted with a Microsoft consent popup to log in to your account.


Mailbox Share

Users can share mailboxes with each other. So far, there is no UI for users to change the ACL in the Mail app, but if you want to use it, you need to enable it on the IMAP sever and configure the shares there.

LLM Processing

The Mail app can optionally use large language models to process emails and offer assistance features like thread summaries, smart replies and event agendas.


The supported languages depend on the used large language model.


A fast text processing integration like is required for best results.

The feature can be enabled in the Mail administration settings.

Administration settings > Groupware > Mail app > Enable text processing through LLMs

Thread Summary

Changed in version 3.6.0: This configuration option was merged into LLM Processing

The mail app supports summarizing message threads that contain 3 or more messages.


A text generation AI integration should be already in place to enable this feature.

The feature is opt-in, it is disabled by default and can be enabled in mail administration settings.

Administration settings > Groupware > Mail app > Enable thread summary