Issue
I need assistance with the setting up of external signature, as it does not appear to be working correctly.
I have setup a signature block for an ad.
This block is set to external users and new email only.
I have added this to the signature.
When I send a test email it shows on the internal email I have as well as the Gmail account I am sending it too.
Please advise as to why this is applying to all emails and not just external users email.
Resolution
Create a Rule based Signature Block.
The signature banner block will have a "Domain" Rule as a selection criteria.

Below is the Rule, which Triggers "False" if the message is sent or cc'd to an Internal User.

Example:
Below is a Signature Block, which only needs to be sent to External recipients:

The Signature Block is added to the Configuration:

Test Message sent to Internal and External Recipients:

Results
Delivered Message after being processed by Crossware:- Internal - the Rule returns False, the Signature Block NOT applied

- External - the Rule returns True, the Signature Block applied

You can find the code here