You don't have to worry about email spam getting you in direct trouble in Google web search. Gary Illyes from Google confirmed that Google won't take action in web search, through a manual action in Search Console, if you get caught spamming folks via email.
Gary wrote on Twitter "the WebSpam team is only looking at web spam," when he was asked "Would Google ever impose manual action (or otherwise) due to email spam?"
Why was he asked this? There is a patent around email spam that mentioned web sites, but I do not think it mention search much. Even so, just because Google may have a patent or research paper, it doesn't mean it is used in web search.
Here are those tweets:
the WebSpam team is only looking at web spam
— Gary 鯨理／경리 Illyes (@methode) January 6, 2021
Forum discussion at Twitter.
