While a simple "Hi," "Hello," or even "Hey" is appropriate in casual correspondence, a more formal salutation is appropriate when you are emailing about a business_related matter, such as a cover letter, letter of recommendation, or inquiry letter.
Even though you are using a personal account, choose an email address that looks professional. Your best bet is some variation on first initial, last name (e.g., [email protected].com) or first name, last name [email protected].com). Here's how to set up an email account just for your job search. Tips for Writing a Compelling Cover Letter. Get information on how to write a cover letter, including what to include in your cover letter, cover letter format, targeted cover letters, and cover letter samples and examples.