How to add signatures to emails sent from shared/group mailboxes

Learn how to configure CodeTwo Email Signatures 365 to add signatures to emails sent from shared mailboxes (cloud/server-side and Outlook/client-side modes) and group mailboxes (Outlook/client-side mode only).

Shared mailboxes are often used to collect incoming emails in a single mailbox, playing the role of a single point of contact for people from outside your organization. These emails can be later answered by one of the designated users responsible for handling high-load communication routes, i.e. email addresses such as [email protected], [email protected], [email protected], etc.

Groups in Microsoft 365 are more collaboration-focused, allowing their members to access services such as SharePoint or Planner. Members from inside or outside your organization (if enabled by an admin) can also use the common group mailbox to send emails.

Basics

This article shows how to configure CodeTwo Email Signatures 365 for a specific email signatures usage scenario. If you need more basic information, use the links below:

How to configure the program for this scenario

Use the links below to learn how to:

Important

When using Outlook (client-side) mode in CodeTwo Email Signatures 365, you can manually add a specific signature to emails sent from group mailboxes. Currently, group objects in Microsoft Entra ID (Azure Active Directory) are missing certain properties, which makes it impossible to automatically add CodeTwo signatures to emails sent from such groups in Outlook or when using cloud (server-side) mode.

Set up user's permissions to a shared mailbox in Microsoft 365

If you do not yet have a shared mailbox, create it in the Microsoft 365 admin center by following these instructions.

To configure permissions to a shared mailbox, open your Microsoft 365 admin center. Then go to Teams & groups > Shared mailboxes and select a shared mailbox from the list (Fig. 1.). In the Manage mailbox permissions section, click the type of permissions you want to edit (Fig. 1., item 3).

Accessing shared mailbox permissions in the Microsoft 365 admin center.
Fig. 1. Accessing shared mailbox permissions in the Microsoft 365 admin center.

Click Add permissions (Fig. 2., item A) and select users that will be allowed to send emails as or on behalf of this shared mailbox, depending on which type of permissions you clicked in the previous step. Confirm by clicking Add. You can remove permissions by selecting a user and choosing Remove permissions (Fig. 2., item B).

Adding (A) or removing (B) users' permission to a shared mailbox.
Fig. 2. Adding (A) or removing (B) users' permission to a shared mailbox.

You might also want to enable message copying to the Sent Items folder if you plan to use the Sent Items Update feature in cloud (server-side) mode. Learn more

How to send emails as or on behalf of a shared or group mailbox

When composing an email in Outlook desktop or OWA, click the From field to expand a drop-down list. Select the desired mailbox if it is already on the list (Fig. 3.).

Selecting a different mailbox as an email sender.
Fig. 3. Selecting a different mailbox as an email sender.

If your mailbox is not on the list, click Other Email Address and type the email address of the mailbox. In your Outlook desktop app, you can also click From to open the Global Address List from where you can select your shared or group mailbox (Fig. 4.). Click OK to confirm and close.

Selecting a shared mailbox from the Global Address List.
Fig. 4. Selecting a shared mailbox from the Global Address List.

If the From field is not displayed in the email compose window:

  • In Outlook desktop, go to the Options tab and click the From button on the ribbon (Fig. 5.).
  • In Outlook on the web (OWA), go to the Options tab and select the Show From checkbox (Fig. 5.).

Displaying the From field in Outlook desktop (left) and OWA (right).
Fig. 5. Displaying the From field in Outlook desktop (left) and OWA (right).

How to set up cloud (server-side) signatures for shared mailboxes

In cloud (server-side) mode, the way signatures are added to emails sent from a shared mailbox depends on users' permissions set for this mailbox:

  • Emails sent by users with the Send as permission will receive a signature configured for the shared mailbox itself. Note that this signature will not contain personalized user's information, e.g. their first name, last name or position.
  • Emails sent by users with the Send on behalf permission will receive a personalized signature, configured for these users.

Important

If you didn't include the shared mailbox in the senders scope when configuring Exchange Online connectors, be sure to add this mailbox to the CodeTwo Exchange transport rule manually, as shown in this article. Otherwise, emails sent by users with the Send as permission to the shared mailbox will not be routed through the CodeTwo service to receive a cloud signature. Make also sure the shared mailbox is included in the scope of licensed users.

If a user is assigned both the Send as and Send on behalf permissions in Microsoft 365, the Send as permission takes precedence and will apply to this user. It is not possible for the user to manually choose their delegate permissions when sending an email.

In the case of Microsoft 365 groups and distribution lists, you can only configure cloud (server-side) signatures for users with the Send on behalf permission. It’s not possible to add a cloud signature to an email sent as a group mailbox or distribution list (this feature is available with Outlook (client-side) signatures only).

Use the links below to learn how to:

Create a signature rule for use with the Send as permission

First, you need to create a signature rule that will add an email signature to messages sent from a shared mailbox. To do this, go to app.codetwo.com, create a new server-side signature rule and name it accordingly, e.g. Shared mailbox for orders (Fig. 6.).

Creating a new cloud (server-side) signature rule.
Fig. 6. Creating a new cloud (server-side) signature rule.

Next, go to the Senders step. Click Add > Selected senders. In the Select users window, find your shared mailbox (e.g. [email protected]) on the list, select it and confirm by clicking OK (Fig. 7.).

Selecting a shared mailbox as a sender.
Fig. 7. Selecting a shared mailbox as a sender.

Configure the other rule conditions and options and prepare a signature template to best suit your needs.

Important

If you plan to use placeholders in the signature template, remember that, by default, shared mailboxes have no contact information or similar details stored in Entra ID (Azure AD). To avoid missing information in the signature for your shared mailbox, fill out the necessary information for the mailbox by editing its properties in the Exchange admin center or our User attributes editor. For example, you can enter the team’s name (e.g. Marketing Team) in the First Name attribute and leave the Last Name attribute empty to get results as shown in Fig. 8.

An example configuration of the First name placeholder for a shared mailbox.
Fig. 8. An example configuration of the First name placeholder for a shared mailbox.

When your signature rule is ready, make sure to apply your changes by clicking the Save & Publish button.

Create a signature rule for use with the Send on behalf permission

If your users have the Send on behalf permission to a shared mailbox, you need to create a signature rule that adds a personalized signature to all emails sent by these users. This can be either:

  • a standard email signature for all employees already in use in your organization

or

  • an email signature designed specifically for the shared mailbox users.

In the case of an existing standard signature, you do not need to make any additional changes to your cloud (server-side) rules. The program will automatically add a signature when an email is sent from a shared mailbox.

If you would like to design a special signature template for the shared mailbox users, read this article on creating signatures for specific senders within a Microsoft 365 organization. Note that this signature will be used in all emails sent by the shared mailbox users, not only in those that are sent on behalf of the shared mailbox.

How to set up Outlook (client-side) signatures for shared mailboxes and groups

In Outlook (client-side) mode, the configuration differs between shared mailboxes and group mailboxes. For specific instructions, click a link below:

Create a Outlook (client-side) signature rule for a shared mailbox

Outlook signatures can be manually added to emails sent on behalf or sent as a shared mailbox.

Important

If you want the CodeTwo Outlook add-in to show signatures configured for a specific shared mailbox after selecting this mailbox in the From field in Outlook, you need to enable the Change CodeTwo Outlook (client-side) signatures based on the From field option first, as described here.

Note that the CodeTwo Signatures Web Add-in for Outlook may not provide full support for shared mailboxes. This is because this type of mailboxes is not yet officially supported by Microsoft on their Office Add-in platform.

You can create a new rule that will be used to add a separate signature template for a shared mailbox or make use of an existing signature rule (and email signature). Either way, go to app.codetwo.com, select the rule you want to edit and go the Senders step. Add the shared mailbox by clicking Add > Selected senders (below the top list) and choosing it in the picker. A sample configuration is shown in Fig. 9.

A shared mailbox added to the senders list of your Outlook (client-side) signature rule.
Fig. 9. A shared mailbox added to the senders list of your Outlook (client-side) signature rule.

Go to the Design step and edit or create a signature template that will be added to emails sent from your shared mailbox. 

Important

If you decided to use an existing signature rule whose design includes Entra ID (Azure AD) attributes (placeholders), remember to also fill out the attributes values for the shared mailbox, as described here.

If you chose to create a separate signature rule and template that will be used specifically for your shared mailbox, you can provide all the details manually in the editor, without using Entra ID attributes.

Finally, configure the remaining options according to your needs and click Save & Publish for the changes to take effect.

Create a signature rule for a group mailbox

In the case of groups, Outlook (client-side) signatures can be manually added to emails sent on behalf or sent as a group mailbox by choosing an appropriate signature with the Use this signature button in the Web Add-in’s pane. This scenario requires you to create a separate signature rule, which lists group delegates as senders.

To start, sign in at app.codetwo.com and create a new client-side signature rule (Fig. 10.).

Creating a new Outlook (client-side) signature for the shared mailbox users.
Fig. 10. Creating a new Outlook (client-side) signature for the shared mailbox users.

Go to the Senders step. Click Add > Group members (inside organization) and select a group containing users with the delegate rights to the group mailbox for which you want to create a signature (e.g. Sales and Marketing, as shown in Fig. 11.). Confirm by clicking OK.

Tip

If no such group exists, click Add > Selected senders instead and select individual group mailbox users from the list or create a new group (see this Microsoft article to learn more).

Selecting a group consisting of users with delegation permissions to this group’s mailbox.
Fig. 11. Selecting a group consisting of users with delegation permissions to this group’s mailbox.

Go to the Logic step, unselect the Set this signature as default for new messages and Set this signature as default for replies and forwards options, as shown in Fig. 12.

Setting up the signature rule so that the signature template for the group mailbox is not added by default to all emails.
Fig. 12. Setting up the signature rule so that the signature template for the group mailbox is not added by default to all emails.

Finally, go to the Design step and create a signature template for the group mailbox, as described here.

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.

If you would like to present different information in the email signature e.g. the email address of the group mailbox or a helpline telephone number, you need to enter them manually when creating a signature template, without the use of placeholders.

Apply your changes by clicking Save & Publish.

Result

In cloud (server-side) mode, if a user sends an email as a shared mailbox (default), CodeTwo Email Signatures 365 recognizes the email as sent by the shared mailbox and adds a signature defined for this mailbox. If a user sends an email on behalf of a shared mailbox, the program adds the signature defined for this user. Both situations are shown in Fig. 13. 

Emails sent on behalf of (left) and as (right) a shared mailbox with cloud (server-side) signatures added by CodeTwo.
Fig. 13. Emails sent on behalf of (left) and as (right) a shared mailbox with cloud (server-side) signatures added by CodeTwo.

In Outlook (client-side) mode, once a user selects a shared / group mailbox in the From field, they need to open the CodeTwo Outlook add-in’s pane and click the Use this signature button next to a signature they want to use (Fig. 14.), i.e. the one configured for the selected mailbox. Learn more about using the add-in

The available Outlook (client-side) signatures are displayed in the CodeTwo Signatures pane in Outlook and OWA.
Fig. 14. The available Outlook (client-side) signatures are displayed in the CodeTwo Signatures pane in Outlook and OWA.

Troubleshooting

If the signature you designed for a shared / group mailbox is not available in the CodeTwo Outlook add-in’s pane, make sure that the option Change CodeTwo Outlook (client-side) signatures based on the From field is configured properly:

  • To support shared mailboxes, the option needs to be enabled.
  • To support group mailboxes, the option should be disabled.

Currently, due to limitations in Exchange Online, the full & parallel support for both types of mailboxes within the same tenant is not possible.

See also

How to add personalized email signatures to emails sent from shared mailboxes

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