When you're writing a business letter or sending an email message, it's important to close your letter in a professional manner. The ideal ending for a business letter conveys your thanks and respect, without eccentricity or an overly familiar tone. Although it may seem old_fashioned, most business professionals expect written correspondence – whether via a letter or an email – to be written and formatted in a conservative manner.
The second version is clearer and thus preferable. Of course, there are exceptions to every rule. What if you are the head of the Global Finance Team? You may want to get your message across without calling excessive attention to the fact that the error was your team’s fault. The passive voice allows you to gloss over an unflattering point—but you should use it sparingly.