Supported platforms and requirements

CodeTwo Email Signatures for Office 365 consists of several components that are responsible for handling server-side and/or client-side signatures:

  • The administrator of a Microsoft 365 (Office 365) tenant configures the software via the 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 are managed using a web app, accessed from the 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 (early access) and Outlook on the web (OWA), 
    • the classic CodeTwo Signatures Add-in for Outlook (COM Add-in) that works with Outlook for Windows only.
  • The core portions of the software that seamlessly process emails and apply signature rules, e.g. the CodeTwo Email Azure Service, 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).
  • 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 web browser:
    • Microsoft Edge,
    • Google Chrome,
    • Mozilla Firefox,
    • Safari.
Signature management app
Required permissions: Only authorized users can access and manage email signature rules. Learn more
Requirements: A modern web browser:
  • Microsoft Edge,
  • Google Chrome,
  • Mozilla Firefox,
  • Safari.

The desktop app will soon be deprecated. Use the new web interface instead – all your rules & settings are available in the new UI.

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 or Windows Server 2019 and newer (older versions of Windows are partially supported*)
  • Outlook for Microsoft 365 (connected to a Microsoft 365 subscription)
    • Version 2106 (Build 14131.20360) and newer
  • Outlook 2019
    • Version 2111 and newer – partially supported*
  • Outlook 2021 – partially supported*
Partial support means that you can use the Web Add-in with the listed versions of Windows and Outlook for Windows to:
  • preview server-side signatures,
  • add client-side signatures manually from the add-in pane.
Outlook for Mac (early access version of the Web Add-in):
  • The new Outlook for Mac (connected to a Microsoft 365 subscription)
    • Version 16.59 (Build 22031300) and newer
Outlook on the web (OWA):
  • A modern web browser:
    • Microsoft Edge,
    • Google Chrome,
    • Mozilla Firefox,
    • Safari.
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.
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 mode used. To allow users working on a client machine to add client-side 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 supported.
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 client-side mode (and in combo mode for client-side signature rules):
  • 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 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 client-side mode and in combo mode for client-side signature rules.

Due to Outlook add-ins' limitations imposed by Microsoft, client-side 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 server-side 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 server-side 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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