Fair enough, that is spam in that case. Your initial comment didn't specify that you have never signed up for a mailing list (except for open source software, which is a mailing list) which I think puts you in the minority of people.
OSS mailing lists shouldn't be considered the same thing because I can send mail to them, and anyone else can as well. They are discussion forums carried out via email.
Mailing lists in the Mailchimp sense are just unwanted advertising in what I view as a communication medium - the equivalent of IRS scammer robocalls.
