CodeTwo Email Signatures for Office 365 can operate in one of three modes:
You first choose the signature mode when registering a Microsoft 365 (Office 365) tenant to our service. However, you can change the signature mode at any time in the CodeTwo Admin Panel. To do so, navigate to Tenants > Manage tenant (), and click Signature modes in the navigation menu on the left. Next, select the signature mode and click Apply (Fig. 1.). Further instructions will be shown on the screen.
A detailed comparison of all three modes is shown in the table at the end of this article.
Server-side signatures are added to emails sent from any email client and mobile device. When CodeTwo Email Signatures for Office 365 works in this mode, you define a scope of senders whose emails are routed through the CodeTwo Email Azure Service to get signatures (Fig. 2.). Email signatures are added to messages sent by or to specific users, based on configured signature rules. Users can preview the signature that will be added to an email by using the dedicated Web Add-in for Outlook for Windows, Outlook for Mac (early access) and OWA; however they cannot make any changes to that signature. Signatures can also be viewed in the Sent Items folder after deploying the Sent Items Update feature.
To enable server-side signatures, you need to configure Exchange Online connectors first. A wizard will guide you through the process.
Watch this video to learn more about the server-side mode and the benefits it brings to a Microsoft 365 (Office 365) organization. If you need more details, see Mail flow in server-side mode.
During the initial configuration of the server-side mode, our software creates connectors in your Exchange Online organization to reroute emails (both internal and external; you can also customize the scope of senders) sent from your Microsoft 365 (Office 365) tenant through the CodeTwo Email Azure Service for processing. When a user sends an email from a Microsoft 365 (Office 365) account (regardless of the email client) as shown in Fig. 3. point 1, this email goes through Microsoft 365 (point 2). The CodeTwo outbound connector redirects the message to the CodeTwo Email Azure Service that checks it against the conditions (rules) configured by an authorized signature administrator in your organization and adds a signature if these conditions are met (point 3). In any case, the email is then sent back (via the CodeTwo inbound connector) to the user's Microsoft 365 tenant (point 4) which delivers it to the final recipient in the usual way (point 5).
If CodeTwo Email Signatures for Office 365 works in the client-side signature mode, signatures are only added to emails sent from Outlook desktop apps and Outlook on the web (OWA) through an Outlook add-in, as shown in Fig. 4. In this mode, emails are not routed through the CodeTwo Email Azure Service and no Exchange Online connectors configuration is required.
To make a client-side signature available for a user, you need to:
- create a client-side signature rule and include that user in the Senders step,
- deploy either of the two signatures add-ins for Outlook:
It is possible to configure the client-side signature rule to automatically insert specified signatures to new messages or replies/forwards (learn more). However, as opposed to the server-side signatures, users can freely choose and edit their signatures in Outlook before sending an email.
Combo mode combines the functionalities of server-side and client-side signature modes (Fig. 5.). The important point is that emails are not routed through the CodeTwo Email Azure Service if they get a client-side signature. A server-side signature is added to emails sent from any email clients other than Outlook desktop apps and OWA. Client-side signatures are added only to emails sent from Outlook where a signatures add-in is deployed. If both a server-side and a client-side signature rule applies to the same user, a signature will be added depending on what email client is used.
If you use the classic CodeTwo Signatures Add-in for Outlook (COM Add-in), server-side signatures will not be added if the Outlook for Windows user has installed the CodeTwo Signatures Add-in for Outlook and is signed in.
The table below presents the features of different signature modes available in CodeTwo Email Signatures for Office 365.
|SERVER-SIDE MODE||CLIENT-SIDE MODE||COMBO MODE|
|Support for all email clients||Yes||Outlook only: Outlook for Windows, Outlook for Mac (early access) & OWA||Yes|
|When is a signature added?||After an email is sent (but you can deploy a Web Add-in to preview signatures as you type an email in Outlook & OWA)||As you type an email||As you type an email in Outlook/OWA or after an email is sent from other email clients|
|Requires setup of Microsoft 365 (Office 365) connectors between your tenant and CodeTwo services||Yes||No
(your emails do not go through CodeTwo services)
(but emails sent from Outlook/OWA are not sent through CodeTwo services)
|Requires deployment of a signatures add-in for Outlook||No||Yes||Yes|
|Can users edit their signatures?||No
(signatures are managed by admins and delegated users)
(only after a signature has been added to an email they are composing)
|Only client-side signatures in Outlook/OWA|
|Support for encrypted/digitally signed (S/MIME) messages||Yes
(if encryption takes place after these messages pass through the CodeTwo Email Azure Service)
(in the case of server-side signatures – only if encryption takes place after these messages pass through the CodeTwo Email Azure Service)