Is it a spambot that rapidly spams one spesific target, or just sends spam to alot of emails on a daily(?) base?
spam filter evasion is not super hard as far as I heard, but it would be nice if you release it you never know when it comes in usefull.
To one specific email, but you can do more if you repeat it with more of it open. All the email goes to the inbox and not spam or junk.