Intepretation Question

When you see two names with a slash in the context of an e-mail, e.g.:

Send the project data to Bill/Betty.

do you read that as “Bill and Betty”, “Bill and/or Betty”, or “Bill or Betty”? How about when they’re separated by a comma, e.g.:

Bill, Betty – Send us the project data.

I see both conventions get used, and as for me, I read a slash as “and/or” and a comma as “and,” but I’m not sure what the popular theory is.