Does email list take away from traffic from a blog?

I recently started a new personal blog, more of a passion than monetized venture (So far), and was wonder if I use my RSS feed to create a subscription / mailing list that mails my latest posts to subs, would this decrease the traffic the site gets due to people reading my posts in their emails? OR would it do the opposite and increase traffic since they could possibly forward emails on of my daily posts?

REMEMBER this is not to mail out offers or make money from yet.

What I do is publish an excerpt to the RSS feed with a link back to my blog to read the full post. This way you get the same advantages of syndication while also pulling people back to your site.