I'm the vendor so I don't know if this will help you but this has been my experience and I work for many companies.

 My orders come in by email. All communications between me and my client are on the same email. I hate it when the don't bother to use the original email to send a question. It wastes my time having to look when I could be out doing a search. The good thing about using the same email string for a specific address is that any time I need to see something I did on it, all I have to do is type the address in the search bar and I can look at everything I've done for the past few years and answer any questions my client may have quickly.