I've noticed that some businesses copy & paste addresses from the shipping address into a Word template for printing mailing addresses on envelopes. That is OK when the shipping address is the same as the mailing address otherwise users need to open the customer card and retrieve the mailing address from there which is always the case with Professional Invoices.
My idea is for an envelope template to be included in the 'Mailing Labels' for each of the Sales Types.
In the meantime a workaround for some businesses in the Service industry is to use a 'Packing Slip' template to construct an envelope template. Unfortunately this cannot be cannot be done for 'Time Billing' sales type as packing slip templates are unavailable.
An example "Invoice-Service - Address Envelope" has been attached to this idea which some client users have adopted; it is for a DL sized envelope 22cms * 11cms. If you use it you would need to set your printer to landscape mode.