Our B2B mobile app for food delivery to businesses sends an email to the recipient as soon as the recipient accepts the delivery on the delivery driver's mobile app. The email contains the signed invoice (bill) for the delivery that was just made. (the signature happens on the mobile device)
Are there best practices I should be aware of for sending invoices/bills via email? What makes a "bad" invoice email vs. a "good" invoice email?
One obvious question is whether I should attach a PDF of the invoice or use HTML content instead, but that seems to be answered well by Sending a formatted email vs. sending a PDF as attachment.
What other questions should I be asking?
Note that this is not a mass-market app but has a focused niche audience with our enterprise support team standing ready to help them, so making sure customers are happiest is more important than reducing chance of any support calls.