Class of Services (COS)#

A COS determines which features and options can be accessed by a user, how to access them, and sets the default values for a number of them.

To create a COS, click the CREATE NEW COS button, enter a name, and optionally a description and some notes. You can then configure all the options by entering the left-hand side Details menu.

General Information#

This section present some (unchangeable) information about the chosen COS: name, ID, and creation date together with some calculated value: which accounts and domains use the COS. These values are expanded below, with the complete list of handled accounts and domains.


Features are settings that allow or forbid the user to access the most used Modules of Carbonio, both via browser and mobile apps. The Administrator can prevent users to even access the Settings module, meaning that the user can not customise anything in the web mail’s Settings. This proves useful in some scenarios: for example, an organisation wants that all the communication of its employees has the same branding (including also Out Of Office replies, the visible name of the sender, and other); another needs that the e-mails be encrypted and does not want users to send plain-text e-mails, and so on.


Some of these options can be enabled or disabled via CLI: please refer to section Setting Features from CLI for more information.


Preferences consist of generic options for the various components (Mails, Calendar, Contacts). Most of these options can be overridden by users in their Settings page.

The first is the default language to be used by the members of the COS, which includes also the locale The list of supported languages can be found in section Available Languages. The remaining options concern

  • the default appearance of Carbonio in web clients: for example, if e-mails are displayed as conversations, or the calendar shows a month or a work week

  • the default values or behaviour of the features: for example whether new e-mail contacts are added automatically to Contacts or how often to check for new e-mails

  • which options are available to the user: for example, whether the user is allowed to forward e-mails or create a filter to forward specific e-mails

  • The default behaviour for sending the read receipt to the e-mail sender: to always send it or not, or asking each time

  • Whether new contacts from which we receive an e-mail are automatically added to the user’s Contacts and if GAL should be used to auto-fill addresses of outgoing e-mails

  • A number of default options for the Calendar: time zone, how the calendar is displayed, and additional option for appointments and events.

Server Pools#

In this page it is possible to select on which servers new users can be added to the COS.


If only one server has been defined, no choice is possible.


Multiple Advanced options can be configured here, divided into multiple groups

General Options

The option in this group allows users of the COS to access the Undelete E-mail feature, which allows each user to retrieve an e-mail from the Carbonio Backup if it was deleted within the last seven days.


This option can be configured on the CLI at both COS and Account level, please refer to Section Setting Features from CLI for details.


Two options govern how to forward messages: how long an e-mail address can be and the maximum number of recipients allowed.


A set of options that show how much space a user can occupy on the server for Mails and Carbonio Files, or how many contacts he can have. These quotas are inherited from the COS the user belongs to and may be changed for the current user. It also encompasses the options to send periodic notifications when the user space raises over a given threshold and a template for the notifications.


Settings for password policies: length, characters, and duration of the user passwords. It is also possible to reject common passwords.


These settings are disregarded if authentication relies on an external server.

Failed Login Policy

Define the behaviour of Carbonio when a user fails a log in.


A typical policy can lock out the user for one hour when three consecutive login attempts fail within 30 minutes.

Timeout Policy

Configure the duration of the token’s validity, i.e., how long a user or Administrator will be able to keep the Web-mail open without interaction.

Email Retention Policy

Define how long e-mail will be stored before being automatically deleted from the Inbox (and its sub-folders), Trash, and Spam folders.

Free/Busy Interop

This option allows to provide O and OU records to display the free/busy user schedule when using an Exchange server.

Limiting Domain Functionalities using COSes#

When Carbonio is configured with multiple domains, it is possible for Global Administrators to limit the amount of accessible Modules, the quota, and the number of accounts available within a domain by employing suitable COSes on the server.

In our scenario, the Carbonio infrastructure defines three COSes:

  • Lite featuring the Mails, Calendars, and Contacts modules and a user quota of 1Gb.

  • Basic with Mails, Calendars, Contacts, and Chats modules and 10GB of quota

  • Pro has full access to all modules and 30Gb of quota

The Global Administrator wants to define a new domain,, limiting the accounts to 200, including 50 Base and 30 Pro.

This scenario can be set up as follows:

  1. Create the new domain (e.g., using the NEW button) and assign it 200 manageable accounts and 30Gb of quota

  2. Select the domain and in its General Settings, scroll to the bottom and select the Lite, Basic, and Pro COSes and assign them the respective number of accounts (120, 50, and 30), then click LINK or DUPLICATE


    By duplicating a COS, it will be named as, e.g., and will be considered as an entirely separated COS. Any change to the original COS will therefore not be propagated to

  3. In the COS list, which is populated while carrying out step #2, select the first one ( as the default one