Stick with plain styling (ASCII text). Write your cover letter in your favorite word processor, but strip away all formatting once you’ve completed editing it by saving the file as “plain text.” Because some email packages allow you to manipulate font style, color, and size, make sure your email is also being sent in plain text — black font, normal size and typeface (10 point, Arial, Helvetica, Times Roman), on a white background.
Check your line length. Make sure your lines are no more than 60 characters in length. Some email packages automatically do word wrap for you (much like word processing software), but you should check. You don’t want your cover letter to arrive fragmented on multiple lines.
Always use standard cover letter protocol. Just because it’s an email, doesn’t mean you should abandon standard business letter writing guidelines. Thus, make sure to include a salutation (Dear Ms. Smith) and a standard closing (such as “sincerely”). Leave blank lines between paragraphs. And avoid the use of emoticons, abbreviations, wild colors, and other cool techniques and shortcuts used in everyday emails.
Don’t bother with attachments (unless requested to do so). Some companies actually block all emails with attachments; thus, your email would never even be received if you used an attachment.
Always follow the company guidelines. Many companies now have career centers on their corporate Websites. (For a list, see the Quintessential Directory of Company Career Centers.) It’s better to take the time and check than to send something the company doesn’t want. For example, Marriott allows you to create a career management account where you can store up to five different resumes and cover letters.
Never hit “send” without thoroughly spell checking and proofreading your email letter. Don’t just rely on your email software’s spellchecker. Take the time to really proofread it. A simple typo could be the downfall of a brilliant cover letter. Avoid all mistakes.