You don’t need to go out of your way. Think about your own inbox for a sec. How many emails are you receiving daily? 10? 20? 100? I’m getting somewhere in between 50 to 60 every day because I need to cut down on the promotional stuff. But your content isn’t promotional — it’s food for thought. You don’t try to sell me anything by sending me a piece that’s already out there waiting to be read by Medium Members. I will say that if your writing contained affiliate links, that would have been more frustrating.
Otherwise, you shouldn’t feel bad about using a tool that helps you communicate with your audience in such a personal way.
Publishing once per day is acceptable. but since you’re posting quite a lot, why not send an email to your list every 2 days? or schedule two times a week: Tuesday and Friday to send out friend links?
Think about it :)