How signatures are added to emails sent as / on behalf of other users
Sometimes a user or a group of users have permission to send messages as other users or on their behalf. These users are referred to as delegates. See the examples below to learn how the software works for users with delegate permissions.
Examples 1 and 2 below apply only to server-side mode and combo-mode. However, in combo-mode, only messages processed by the CodeTwo Azure Email Service will be processed as presented in the examples below.
Example 1: User A has the Send As permission to the User B's mailbox. When User A sends an email and enters User B's email address in the From field, the message will be considered as sent by User B. Therefore, the rules covering User B will be executed (the email will get User B's signature) and the SIU service will update the message in the Sent Items folder of User B.
Example 2: User A has the Send On Behalf Of right on User B's mailbox. When User A sends an email and types the email address of User B in the From field, the message will be considered as coming from User A, and the rules covering User A will be executed (the email will get User A's signature). The SIU service will update the Sent Items folder of User A.
In the case of client-side mode, the user will have to select one of the signatures available in CodeTwo Email Signatures for Office 365 when using Send As or Send on behalf. The same applies to messages sent in combo mode that are processed according to client-side rules (i.e. not processed by the CodeTwo Azure Email Service), as shown below, in example 3.
Example 3: User A has the Send As / Send On behalf permission to the User B's mailbox. When User A creates an email, a signature is added directly in Outlook by CodeTwo Email Signatures for Office 365. The message is considered as coming from User A’s Outlook email client, therefore client-side rules applicable to this User will be used. The User should select a signature appropriate to the message being sent from among the available ones.
If you want to know more, see our Knowledge Base article for examples with screenshots.
In order for the SIU service to work as described above, you need to enable message copying in your Exchange Online, as described in this Microsoft blog article.