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 and enter a name. You can then configure all the options by entering the left-hand side Features 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 them 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 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

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.


The Advanced Option allow to configure the user quota, passwords, policies, and more.

The user quota, is a set of options that limit how much space a user can occupy on the server, or how many contacts he can have. It also encompasses the option to send periodic notifications when the user space raises over a given threshold.

The Password settings permit to tune the length, characters, and duration of the user passwords. It is also possible to reject common passwords.

The Failed Login Policy allows to 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.

The Timeout Policy concern the duration of the token’s validity.

The Email Retention Policy define how long e-mail will be stored before being automatically deleted.

Finally, the Free/Busy Interop 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