Supported platforms and requirements

CodeTwo Email Signatures 365 consists of several components that are responsible for handling email signatures and automatic replies:

  • The administrator of a Microsoft 365 (Office 365) tenant configures the software via CodeTwo Admin Panel, a web-based interface for registering new tenants to the service, accessing signature management as well as managing payments and other tenant-related options.
  • Email signatures and automatic replies are managed using a web app, accessed from CodeTwo Admin Panel or directly at Only the tenant's global admins and users delegated by the admin can use this app.
  • There are two add-ins that allow users to add signatures to emails directly in Outlook as they type a new message. You need to deploy either of them:
    • (recommended) the modern CodeTwo Signatures Web Add-in for Outlook that works with Outlook for Windows, new Outlook for Mac and Outlook on the web (OWA), 
    • the legacy CodeTwo Signatures Add-in for Outlook (COM Add-in) that works with Outlook for Windows only.
  • The User attributes manager lets you quickly edit end users' information (individually or in bulk) shown in email signatures and automatic replies. End users can also manage their own information if they are allowed to do so by the admin.
  • The core portions of the software that seamlessly process emails and apply signature rules (the CodeTwo cloud services) run on Microsoft Azure servers and are operated by CodeTwo, so they are not listed in the detailed requirements below
CodeTwo Admin Panel
Required permissions:

Microsoft 365 global admin rights* (required for specific actions only).

* CodeTwo does not store, copy or have access to your global admin credentials. We use the safe OAuth 2.0 protocol that allows our cloud solution to access only limited and absolutely required data in your tenant by means of an access token granted by Microsoft’s servers.

  • Microsoft 365 (Office 365) plans with Exchange Online (access to Exchange Online transport rules is required; F1 and Kiosk plans are also supported).


The above Microsoft 365 plans store data in the Azure AD cloud, and access to Azure AD is required by the CodeTwo software. A separate Microsoft Azure subscription is not required for any of these plans.

Trial Microsoft 365 subscriptions are supported as well.

  • A modern, up-to-date web browser such as Google Chrome, Mozilla Firefox, Microsoft Edge, Safari, etc.
Signature & autoresponder management (
Required permissions: Only authorized users can access and manage email signature and autoresponder rules. Learn more
Requirements: A modern, up-to-date web browser such as Google Chrome, Mozilla Firefox, Microsoft Edge, Safari, etc.
CodeTwo Signatures Web Add-in for Outlook (Outlook for Windows, Outlook for Mac and Outlook on the web / OWA)
Required permissions: Microsoft 365 Exchange admin or global admin rights (required for deployment only).


Outlook for Windows:
  • Windows 10 (Version 1903, Build 18362) or Windows Server 2019 (Version 1903) and newer – older versions of Windows are partially supported*
  • Outlook for Microsoft 365 (Version 2108, Build 14326.21018) and newer – Microsoft 365 subscription required
  • Outlook 2019 (Version 2111) and newer – partially supported*
  • Outlook 2021 – partially supported*

Both 32 and 64-bit versions of Outlook for Windows are supported.

Partial support means that you can use the Web Add-in with the listed versions of Windows and Outlook for Windows to:
  • preview CodeTwo cloud signatures,
  • add CodeTwo Outlook (client-side) signatures manually from the add-in pane.
Outlook for Mac:
  • The new Outlook for Mac (Version 16.59, Build 22031300) and newer – Microsoft 365 subscription required


The New Outlook toggle in the upper-right corner of Outlook for Mac needs to be set to On. If you don't see the toggle, click Outlook in the menu bar and select New Outlook.

Outlook on the web (OWA):
  • A modern, up-to-date web browser such as Google Chrome, Mozilla Firefox, Microsoft Edge, Safari, etc.
CodeTwo Signatures Add-in for Outlook (Outlook for Windows)
Required permissions: To install the add-in, no administrative credentials are required. However, if the required version of .NET Framework is missing, a user must have administrator privileges to install it.
Requirements: Outlook:
  • 32 or 64-bit versions of Outlook 2013 or later,
  • at least Windows 7 SP1 or Windows Server 2008 R2 SP1,
  • .NET Framework 4.7.1.
User attributes manager
Required permissions: Microsoft 365 global admin rights are required to access, a web interface used to manage end users' details stored in CodeTwo Azure AD cache.
Requirements: A modern, up-to-date web browser such as Google Chrome, Mozilla Firefox, Microsoft Edge, Safari, etc.
Notes and

The software supports multi-factor authentication.

Signatures cannot be added to native out of office messages (automatic replies). Instead, you can create your own auto replies and add signatures to them by using the Autoresponder feature. Learn more
The software is compatible with both Windows Virtual Desktop (WVD) and Terminal Server (RDS) environments, regardless of the signature mode used. To allow users working on a client machine to add CodeTwo signatures in Outlook or OWA, you need to deploy the modern CodeTwo Signatures Web Add-in for Outlook for these users via the Microsoft 365 admin center. Learn more
In hybrid environments, our software can process only emails going through Microsoft 365 (EOP) servers. See this article to learn how to use CodeTwo software in different hybrid deployments.
Shared mailboxes are fully supported in the cloud (server-side) signature mode. In Outlook (client-side) mode, the CodeTwo Signatures Web Add-in for Outlook works with shared mailboxes but may not provide full support. This is because shared mailboxes are not yet officially supported on the Microsoft's Office Add-in platform.
Microsoft 365 DKIM-signed emails are supported.
Microsoft Planner notifications are supported. Learn more
Emails sent from aliases (using an alias as the email sender) are supported. Learn more
The following message types are only supported in the Outlook (client-side) signature mode (and in combo mode when using CodeTwo Outlook signatures):
  • messages sent as groups (e.g. Microsoft 365 groups), distribution lists and contacts,
  • messages sent from mail-enabled public folders.

Learn how to add group-specific signatures to emails sent as / on behalf of these groups

Messages digitally signed and encrypted via Office 365 Message Encryption / Azure Information Protection (Azure RMS and related features: Encrypt-Only, Do Not Forward, sensitivity labels) or by other encryption technologies (e.g. S/MIME, PGP or OpenPGP such as GPG) are supported in the Outlook (client-side) signature mode and when using CodeTwo Outlook signatures in combo mode.

Due to Outlook add-ins' limitations imposed by Microsoft, CodeTwo Outlook signatures are not added when replying to / forwarding encrypted or IRM-protected messages in Outlook on the web (OWA). Learn more on Microsoft's site

In the cloud (server-side) signature mode, encrypted/digitally signed messages will be stamped with signatures only if encryption takes place after these messages pass through the CodeTwo services. The same applies when using CodeTwo cloud signatures in combo mode.

Impact of the software on your IT infrastructure Changes to operating system:
Changes to Microsoft 365 (Exchange Online):
  • After registering your Microsoft 365 tenant in CodeTwo Admin Panel, a new accepted domain is automatically added to your tenant: [your unique ID]

See also

Deployment steps and software configuration - a list of useful links that will help you deploy the program and use it with your Microsoft 365 (Office 365) tenant

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