You wish to update the group that is assigned to receive server-side injection within Signature 365.
The security group can be updated in either of 2 methods, both of which are detailed below.
If you wish to apply the rule to multiple groups, it is only possible to configure this through the Exchange Admin center.
Please note that if these groups are updated within the exchange admin centre, this change will not be reflected in the Signature 365 portal.
To update this group using Signature 365, use the following link:
This will take you through the exchange setup process and allow you to update the group selected, or apply server-side signatures to all users.
Log on to the Microsoft Exchange Admin centre, and select the Send to Signature 365 for signature injection rule.
Select the Edit rule conditions option in the flyout.
Under the Conditions tab, click the edit button to update the The sender is a member of this group option, selecting the group you would like to use.
Deleting the The sender is a member of.... conditional statement will apply the rule to all users.