Cover letters should be free of errors, so thoroughly proofread them before sending. If proofreading is not your strong suit, get help from someone with meticulous proofreading skills. If you're customizing a cover letter that you use for many positions, remove any placeholders; this will prevent embarrassing errors such as" it would be delighted to be your next?" And one last tip: whatever you do, please spell the hiring manager's name correctly.
SOURCE: Cover Letter Etiquette
by Kim Isaacs
Monster Resume Expert