Email to subscribers off my blog - yes or no

[bestfreeporn]

I have email subscribe links on most of my blogs. Not everyone one every blog signs up. Is it alright to email them about my other blogs or does the email have to be about the specific blog they subscribed through.

If you have not done already add a line in the terms they agree to when accepting email form your site that at times you may include special offers from your other sites.