Task
Following the creation of the signature templates in the online portal, you will need to create a rule to apply the signature to a user or group.
Rules are applied in priority order, ascending from 1.
If you do not have any existing rules, you will see the following screen - hit "Create a rule now" to add a new rule, otherwise, click + Add to add a new rule.
This will display the new rule screen - set a name and description as desired.
The Apply to option allows you to define from several options to determine which users the rule will be applied to. You must have integrated Signature 365 to your Office 365 tenant and imported users / groups.
All users as the title, will apply this rule to all users of the system.
Specific groups and users will apply this rule to any group and/or users selected.
Specific email domains allows you to select any registered domains that exist on your Microsoft 365 tenant.
The Users filtered by attributes option allows for advanced configuration options. These allow for rule checks based on From, Sender and Message types:
The From and Sender filter can be applied against any field that exists within Signature 365. For example, using From -> Email -> Contains can be used to test on an email alias to apply a specific signature based on the from address of the email.
The Message option allows a rule to evaluate specific message properties:
Sent on behalf of is a Yes / No field based on if the email is sent on behalf of another mailbox.
From email address and Sender email address allow specific checking of the email address the email is sent from.
Source system allows checking of the source email client to define a specific signature - for example a mobile device or Outlook Web Access.
The Match rule on Sender instead of From... tickbox is available for the groups and users and email domains options, is enabled by default and applies when sending emails from shared mailboxes. This option matches the rule based on the sender of an email, as opposed to the mailbox it is being sent from.
The Default signatures section allows you to choose how this rule should be applied - either New emails and replies/forwards, or Internal / External.
Dependent on the selection, the available options will apply signatures to New / Reply, or Internal / External. The default signature for each selection can be chosen from the dropdown box.
An Internal / External email is determined by the recipient addresses, and will always apply the external signature if any recipient is not a member of your Exchange email domains.
Use details of sender instead of from..... tickbox is enabled by default and configures the rule to use the details of the mail account sending the email when sent from a shared mailbox, as opposed to using the details of the additional mailbox. This allows email sent from a shared mailbox to display information about the user sending on behalf of the shared mailbox.
Allow users to change default signatures is disabled by default - this allows users assigned to this rule to select their default signature if they have been assigned additional signatures.
Additional signatures allows you to configure multiple signatures to be made available for this rule, if you have more than one signature available.
The "Stop processing more rules" option is used to prevent rules of a lower priority from being applied to a user, group or domain when this rule is triggered.
Hit the "create rule" to create the rule