Error in file attachment in email. Azure bucket url. Throwing error path does not exist

1 
frappe.sendmail(
    recipients=recipients,
    sender='user@zapspremium.com',
    subject='ID '+ doc.name + " Booking Confirmation",
    template=doc.status,
    args={
        'bookingId': doc.name,
    },
    now=True,
    attachments=[{"file_url": doc.voucher_pdf}],
)

Earlier this was working fine when the file was uploaded on the server itself. Now we are uploading the file on Azure bucket and its URL is stored in this field
{
“voucher_pdf”: “https://zapspremiumblobstorage.blob.core.windows.net/static-content/voucher.pdf”,
}

Now it is not working and the throwing error path does not exist. how can I make it work??