I'm […] from [company]. We absolutely love your blog and how you interact with your audience.
We'd like to offer you [product/offer], which you can use as a giveaway on your blog. I believe this could be of great benefit for you. You’ll also be getting [offer] in return for hosting the contest.
If you’re interested, let’s discuss the details further over a call some time this week. Keep up the awesome work on your blog!