Selling sourdough online by courier

If I have been appointed as a courier to sell someone’s acid, can I do this via the Internet?
That is, from what I remember from frontal sales, there are two forms of bills of exchange, one for the seller’s own account and one for the seller’s account of a forwarder. However, on the sales sites, I did not find a form for a sale by courier. Would it be useful to simply fill in the details with the person’s name?