Relevant Products: Signature Manager Exchange Edition
This scenario typically occurs where there is a hybrid environment (i.e. where both Office 365 and an on-premise Microsoft Exchange Server are in use), or where customers are gradually migrating from an on-premise Microsoft Exchange Server to Office 365.
Duplicate signatures may occur when an Office 365 user emails an on-premise Exchange user, and vice versa. Because the message is processed by both Exclaimer solutions, a signature is appended on both occasions.
To resolve this issue, you need to take steps in both products:
Preventing a second signature being appended by Signature Manager Exchange Edition
To prevent a second signature being appended by Signature Manager Exchange Edition, you should add a word or phrase exception in the appropriate signature policy (within Signature Manager Exchange Edition). Please see the resolution in this article for details.
The word or phrase that you specify as the exception should be present in the signature being deployed from Office 365 (for example, a company registered number). The result will be that any email sent from Microsoft Outlook with the Office 365 signature already appended, will be excluded from having a second signature appended by Signature Manager Exchange Edition.
Preventing a second signature being appended by Office 365
To prevent a second signature being appended by Office 365, you should add an exception to the Identify messages to send to Exclaimer Cloud transport rule. To achieve this, please follow solution instructions in this article. However, instead of using an email domain as the exception, use a word or phrase from the message body. The word or phrase that you specify should be present in the signature being deployed from Signature Manager Exchange Edition (for example, a company registered number).