The part of the sentence 'I am contacting you because' is correct and usable in written English. You can use it to explain the reason for your contact. For example: "I am contacting you because I need advice on how to improve my essay writing skills.".
Such as: "I am contacting you because" or "I recently heard about...and would like to know more about…".
Begin the letter with: "I am contacting you because you have an outstanding balance on your account from March 2015 .. Or, you are an employee at a company and are writing in response to a customer complaint against the company's space program.
Hi There, I'm contacting you because you have a Twitter account for which we enabled something called "autofollow".
For example, I've had people tell me, "I'm contacting you because we both serve Audience X".
Dear Google Alerts user, We're contacting you because you have an alert of type Web.
Hello, I'm contacting Uber support because I'd like to have my account deleted.
"It's pretty clear that they are contacting me because I am the most like them," he said.
I love the desktop app, it’s always running on my Mac. Ludwig is the best English buddy, it answers my 100 queries per day and stays cool.
Cristina Valenza
Retail Lead Linguist @ Apple Inc.