Supported platforms and requirements

CodeTwo Email Signatures 365 consists of several apps and services that are responsible for handling email signatures, automatic replies and one-click surveys:

  • 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 app.codetwo.com. Only the tenant's global admins and users delegated by the admin can use this app.
  • CodeTwo Signatures Web Add-in for Outlook (Web Add-in) lets users add signatures to emails directly in Outlook as they type a new message. It works with Outlook for Windows, Mac, Outlook on the web (OWA), iOS & Android.
  • CodeTwo Insights (insights.codetwo.com) is a customer satisfaction analytics tool that gathers ratings from your one-click surveys. 
  • The Attributes manager app lets admins create custom CodeTwo attributes and quickly edit end users' information (individually or in bulk) cached by CodeTwo and shown in email signatures and automatic replies in your organization.
  • The My user info app allows end users to manage personal information shown in their signatures & auto replies.
  • 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.

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

Info

The above Microsoft 365 plans store data in the Entra ID (Azure AD) cloud, and access to Entra ID 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.

  • The most up-to-date version of a popular modern web browser (such as Google Chrome, Mozilla Firefox, Microsoft Edge and Safari).
Signature & autoresponder management (app.codetwo.com)
Required permissions: Only authorized users can access and manage email signature and autoresponder rules. Learn more
Requirements: The most up-to-date version of a popular modern web browser (such as Google Chrome, Mozilla Firefox, Microsoft Edge and Safari).
CodeTwo Signatures Web Add-in for Outlook (Outlook desktop, mobile & OWA)
Required permissions: Microsoft 365 Exchange admin or global admin rights (required for deployment only).

Requirements:

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 2021/2019/2016 retail (Version 2308, Build 16731.20170 and newer) – older versions are partially supported*

Both 32 and 64-bit versions of Outlook for Windows are supported. Also note that Microsoft has ended support for signing in to Microsoft 365 services with Office 2019 and Office 2016, so the retail versions of Outlook 2016 and 2019 might stop working soon.

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.

New Outlook for Windows:

The Web Add-in works with the new Outlook for Windows but some features might not work as expected because the new Outlook is still in preview (beta) and Microsoft's changing a lot in it. If you experience any issues, let us know and we'll report to Microsoft. For the best add-in experience, we still recommend using standard Outlook.

If you have multiple email accounts in Outlook, you will be able to use the Web Add-in with the primary account only. This is due to the current limitations of the new Outlook for Windows.

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):
  • The most up-to-date version of a popular modern web browser (such as Google Chrome, Mozilla Firefox, Microsoft Edge and Safari).
Outlook for iOS and Android (early access):
CodeTwo Insights (insights.codetwo.com)
Required permissions: Microsoft 365 global admins and authorized users can access insights.codetwo.com, a web interface used to view the statistics of one-click surveys set up for your organization. Learn more
Requirements: The most up-to-date version of a popular modern web browser (such as Google Chrome, Mozilla Firefox, Microsoft Edge and Safari).
Attributes manager (attributes.codetwo.com)
Required permissions: Microsoft 365 global admin rights are required to access attributes.codetwo.com, a web interface used to manage end users' details stored in CodeTwo Azure AD cache. Learn more
Requirements: The most up-to-date version of a popular modern web browser (such as Google Chrome, Mozilla Firefox, Microsoft Edge and Safari).
My user info (user.codetwo.com)
Required permissions:

Microsoft 365 account is required to access users.codetwo.com, a web interface used to manage end users' shown in email signatures and auto replies. Learn more

The My user info app will not work unless an admin sets up attributes.codetwo.com first, as shown here.

Requirements: The most up-to-date version of a popular modern web browser (such as Google Chrome, Mozilla Firefox, Microsoft Edge and Safari).
Other 
Notes and
warnings:

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 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 works with shared mailboxes in Outlook desktop apps & OWA but might 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
The software supports tenants with multiple domains added.
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.

Important

If you use placeholders in a signature template, the information displayed in an email signature such as email address or telephone number will be taken from the Entra ID (Azure AD) account of a user who sends an email as or on behalf of a group mailbox.

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.

Both cloud and Outlook signatures are added to emails with the Public sensitivity label assigned in the same way as to emails with no labels.

The maximum supported message size limit is 150 MB (including attachments). This matches the limit set by Exchange Online. 

However, if you are using CodeTwo Email Signatures 365 in cloud (server-side) mode, the maximum supported message size is 110 MB. This is because when an email travels though the CodeTwo service, it is subject to Base64 encoding (used by Exchange Online) and, as a result, its size might temporarily increase by about 33%. You might consider adding the following exception to the CodeTwo Exchange transport rule: The message > size is greater than or equal to 112640 KB. By doing so, emails larger than 110 MB won't be processed by CodeTwo (and won't get cloud signatures). Alternatively, use a file hosting service (such as OneDrive for Business) to send links to large files rather than attaching such files to your emails.

Outlook (client-side) signatures are not routed through CodeTwo, so their size is not increased (the size limit is 150 MB). 

Impact of the software on your IT infrastructure 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].smtp.codetwo.online.

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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