Hi [Prospect Name],
My name is [Your Name] and I'm the [Your Title] at [Your Company]. We're a link building agency that helps businesses improve their search engine rankings by building high-quality links.
I'm reaching out to you today because I'm interested in collaborating with you on a guest post. I think our two companies would be a great fit for each other and I think we could create a valuable piece of content that would benefit both of our audiences.