In a cover letter, keep your remarks brief. Your opening should explain what you are sending and why. In an optional second paragraph, you might include a summary of the information you are sending. A letter accompanying a proposal, for example, might point out sections in the proposal that might be of particular interest to the reader. The letter could then go on to present a key point or two explaining why the writer’s firm is the best one for the job. The closing paragraph should contain acknowledgements, offer additional assistance, or express the hope that the material will fulfill its purpose
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.