As far as I can tell there is no real connection between email spam and SEO, but I have a hard time explaining any other way.
Site: local marketing agency with major clients, good profile and decent SEO stats (I've done local SEO audit) by all accounts they should be up top or at least somewhere in the middle. They did mention when they bought the domain their emails were going to spam if there was even a mention of that domain name in the email because of previous owners. They worked with gsuite and spamlists to get the domain delisted. So hypothetically all is good.
The problem is their SEO stats is OK, all their pages are listed but in terms of competitive SEO they are non-existent. Besides their company name they are not ranking for any terms I checked to pages 10+ (for reference a site I made in a similar niche 6 months ago with no optimization is on page 3).
I am scratching my head what is going on? Is there any way to contact Google to ensure they are not penalized? I am reluctant to do any more optimization until this is resolved.