Email spam is universally defined as unsolicited bulk email.
You need a definition that can withstand a court challenge. Grouping vague, undefined terms does not do the trick. If I post my e-mail address in a whois database or post it on a web site am I soliciting e-mail? How many is "bulk"? So if I send you, and only you, an ad after I collect your address from this list it is not "spam" because I did not send it in bulk? When you get a single message, using your definition, you can't tell if it is spam because you don't know if it was sent in "bulk" (whatever that means). Even if you see similar reports from many different sources if they came from different IP's you still can't tell if it was spam because if different people sent the messages it may not qualify as "bulk." I don't know anyone that actually uses such a standard, in practice, to define "spam."