Technically there’s no authority to determine if you ever did “opt in”, so that is a moot point. I get spam all the time claiming I opted in, when I know I’ve not. Nothing in an email is a guarantee, to include statements that you wanted this email or agreed to be contacted.
Technically it’s not considered spam if you opted in. Spam is unsolicited mail.
Technically there’s no authority to determine if you ever did “opt in”, so that is a moot point. I get spam all the time claiming I opted in, when I know I’ve not. Nothing in an email is a guarantee, to include statements that you wanted this email or agreed to be contacted.