Signature modes

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 (ESIG for O365 settings button2 13px), 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.

The Signature modes page in CodeTwo Admin Panel.
Fig. 1. The Signature modes page in CodeTwo Admin Panel.

A detailed comparison of all three modes is shown in the table at the end of this article.

Server-side mode

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 add-in for OWA and Outlook; 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.

A diagram showing CodeTwo Email Signatures for Office 365 working in the server-side mode.
Fig. 2. A diagram showing CodeTwo Email Signatures for Office 365 working in the server-side mode.

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.

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).

Mail flow in Microsoft 365 (Office 365) with CodeTwo Email Signatures for Office 365 in server-side mode.
Fig. 3. Mail flow in Microsoft 365 (Office 365) with CodeTwo Email Signatures for Office 365 in server-side mode.

Client-side mode

If CodeTwo Email Signatures for Office 365 works in the client-side signature mode, signatures are only added to emails sent from Outlook for Windows and Outlook on the web (OWA), as shown in Fig. 4. To make a client-side signature available for a user, you need to:

In client-side mode, CodeTwo email signatures are available as you type an email in Outlook & OWA, and are updated automatically via a dedicated Outlook add-in.
Fig. 4. In client-side mode, CodeTwo email signatures are available as you type an email in Outlook & OWA, and are updated automatically via a dedicated Outlook add-in.

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

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 for Windows 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.

Important

If you use a classic CodeTwo Signatures Add-in for Outlook (COM Add-in), server-side signatures will not be added if the Outlook user has installed the CodeTwo Signatures Add-in for Outlook and is logged in.

A diagram showing CodeTwo Email Signatures for Office 365 working in the combo signature mode.
Fig. 5. A diagram showing CodeTwo Email Signatures for Office 365 working in the combo signature mode.

Signature modes comparison

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 for Windows and OWA only Yes
When is a signature added? After an email is sent (but you can deploy a Web Add-in to preview a signature as you type an email in Outlook, OWA and Outlook for Mac) 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)
Yes
(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)
Yes
(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)
Yes Yes
(in the case of server-side signatures – only if encryption takes place after these messages pass through the CodeTwo Email Azure Service)

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