Hello @BikurCholim ,
Since PDFs can't be embedded into emails, they're instead added as images. Typically most customers will link this image directly to the PDF, or rely on the system to do it automatically - such as in the case of PDF-created emails.
If you're just wanting to include the image of the flyer, and there's no other links in the PDF you're wanting contacts to be able to click on, then I'd advise just setting up that image to link directly to your site. I'd also advise adding some additional text or other content, since image-only emails can get caught in more aggressive spam filters.
See also:
Text links
Button links
Inserting documents
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