From reviewing your site it appears to be an official Microsoft website as you are using their trademarked logos as your favicon, the Microsoft design style and

From reviewing your site it appears to be an official Microsoft website as you are using their trademarked logos as your favicon, the Microsoft design style and all around the site without properly notifying visitors up front that you are not officially affiliated with Microsoft. If you are, then you should have this listed on the site and link to your partner status validation with Microsoft. This is why it has been marked as a phishing site due to not properly identifying your affiliation. There is no footer with the details of the business behind the site and the about us page does not properly identify your company or business information which is very common on phishing websites. Best practice is to come up with a unique web design that is not easily comparable to the products main vendor that you are creating a service for. Once you have properly identified the site and changed the design you might be able to get unsuspended, but for now the site looks and feels like a phishing website.