For the moment, there are no way to do this from Pegasus version 2, but there is a way to achieve this from Pegasus version 1. Follow these instructions:
1. Create a signature in Word or your favorite editor, and Save it as an html file:
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2. Login to Pegasus version 1:
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3. Upload it following this path: Appearance -> Mail Signature
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4. Select the file you created in point number 1, and click on “Save Button”