There's an entire cottage industry of linkedin scrapers that put a lot of effort into guessing your email address to enable cold outreach.

I'm ashamed to say I worked at one such place for several months.

Apollo is probably the most comprehensive source for this. It's creepy as fuck.

Yes I notice that too. I hide my last name now because at my company it's just firstname.lastname so easy to guess.

It helps a lot but I still get a lot of sales goons. A lot of them follow up constantly too "hey what about that meeting invite I sent you why did you not attend"? My deleted email box is full of them (I instantly block them the minute I get an invite to anything from someone I don't know, and I wish Outlook had the ability to ban the entire origin domain too but it doesn't)