Submitting effective cover letters to your employer would definitely give you an advantage ahead of the personal meeting. Therefore, it is just necessary to make your cover letter be perfect as possible. Though there are no certain requirements on what you should strictly include on your cover letter or resume, you should always consider using correct grammar and spelling every time you write one. Most employers give first impressions on documents written by their applicants especially if the nature of work requires excellent communication skills.
There are certain ways that you may want to consider to make sure that your cover letter would have the quality that can impress the recipient. To check grammar of the cover letter or resume you have written conveniently, you should turn on the spelling and grammar check settings on your word processor. However, you should not mainly rely on the automatic settings. It is still best to double check your letter before printing it out or sending it to your employer online.