I assume you're being facetious, but there is a literal definition of SPAM in the United States (or, at least, a definition whereby it's OK to send 'commercial email', the inverse of which could be considered SPAM). (From Wikipedia for the CAN-SPAM act - https://en.m.wikipedia.org/wiki/CAN-SPAM_Act_of_2003#Applica...)
A commercial email is legal if it complies with the following:
Unsubscribe compliance
* A visible and operable unsubscribe mechanism is present in all emails.
* Consumer opt-out requests are honored within 10 business days.
* Opt-out lists also known as Suppression lists are only used for compliance purposes.
Content compliance
* Accurate "From" lines (including "friendly froms")
* Relevant subject lines (relative to offer in body content and not deceptive)
* A legitimate physical address of the publisher and/or advertiser is present. PO Box addresses are acceptable in compliance with 16 C.F.R. 316.2(p) and if the email is sent by a third party, the legitimate physical address of the entity, whose products or services are promoted through the email should be visible.
* A label is present if the content is adult.
Sending behavior compliance
* A message cannot be sent through an open relay.
* A message cannot be sent without an unsubscribe option.
* A message cannot be sent to a harvested email address.
A commercial email is legal if it complies with the following:
Unsubscribe compliance
* A visible and operable unsubscribe mechanism is present in all emails.
* Consumer opt-out requests are honored within 10 business days.
* Opt-out lists also known as Suppression lists are only used for compliance purposes.
Content compliance
* Accurate "From" lines (including "friendly froms")
* Relevant subject lines (relative to offer in body content and not deceptive)
* A legitimate physical address of the publisher and/or advertiser is present. PO Box addresses are acceptable in compliance with 16 C.F.R. 316.2(p) and if the email is sent by a third party, the legitimate physical address of the entity, whose products or services are promoted through the email should be visible.
* A label is present if the content is adult.
Sending behavior compliance
* A message cannot be sent through an open relay.
* A message cannot be sent without an unsubscribe option.
* A message cannot be sent to a harvested email address.
* A message cannot contain a false header.
* A message should contain at least one sentence.
* A message cannot be null.
* Unsubscribe option should be below the message.