Ideal frequency of outreach mails?

Maybe I'm just a terrible curmudgeon, but I find the number of emails I receive from services I sign up for to be totally egregious. Everyone wants you to sign up for their mailing list these days, and when you're on it it's not uncommon to get an email daily, or three times a week, or weekly. I end up tuning them out and deleting them unread, or when they are daily I just unsubscribe. My question is a two-parter: 1) is this just me? 2) what, in your opinion, is the ideal frequency to send mails to users? I think striking a good balance here is quite hard.