From Indeed.com:
More and more, we are submitting job applications over email but don't be overly relaxed about it! There is a right way and a wrong way to do this! See the tips below.
Use the following tips to write a professional email that makes a positive impression on employers:
Find an actual person to address in your email
Take a look at the company website to identify the name of a supervisor or director who oversees the department you would most likely work in. This is a technique that you can use to appeal as a personable individual to an employer. By directly addressing an individual by name, you are demonstrating that you have completed company research which further demonstrates your enthusiasm for the job.
Use the right email address
Make sure that you are using a professional email address. Sending an email application from an email address such as [email protected] can be seen as an immediate disqualification because it's unprofessional. Consider using an email that uses your first and last name or initials only, such as [email protected].
Add the recipient's email address last
This is important in preventing you from clicking send before you have thoroughly checked for mistakes. Only add the email address once you are sure that your message is free of grammar and punctuation errors and you have the appropriate documents attached.
Keep your message short
A proper application email should be short and direct, only including the most relevant information. Employers might be deterred by long and wordy messages when they have other applications to review.
Check your attachments' names