Issue – when sending emails from transactions, the attachment sending as HTML doc rather than a PDF
Solution: The email preference in the customer record may have been set ‘Default’ value. And in Set preferences(under the Home tab), the Transaction Email attachment format may be set as HTML (Under the transactions tab).
Then when sending emails for the transactions of this customer, the type of attachment will be selected as ‘Default’ and then the attachment will be in HTML format.
So changing the format in the customer record or in the preferences will solve the issue