Job seekers often spend hours perfecting their resumes and agonizing over their cover letters, and then blow it all by sending an email that comes across as unprofessional. Here are 10 ways that a single email can ruin your chances of getting an interview or job.

1. Sharing an email account with a spouse. Employers don’t want to feel like they are emailing job-related correspondence to your significant other. If your email address makes it clear that someone shares it with you then it’s time to get your own separate account for job-searching. They’re free, after all.

Unprofessional email signature
2. Using an unprofessional email signature. If your email signature contains political or religious messages, long quotations, or inspirational messages, you risk turning off your recipient and signaling that you don’t know what’s appropriate for professional communications.

3. Using unusual fonts. There’s a fairly narrow range of acceptable fonts for emails. If you’re using Comic Sans, you’re going to come across as unprofessional and a bit uncomfortable with technology. A good email font is one that doesn’t make the reader think about what font you used.

4. Using email stationery. Email isn’t a written letter; it doesn’t require stationery. Using borders of flowers around your email text looks tacky and unprofessional.

5. Making recipients jump through anti-spam hoops to respond. We all want to get less spam, but if you make someone fill out an anti-spam form to get their email through to you, then you might find that some employers just don’t bother.

6. Not checking your spam folder. If you’re conducting a job search, make sure that you check your spam folder every day. A surprising number of emails from employers can end up in there. You might sit around wondering why no one has gotten back to you when in fact there is a response or two in your spam folder right now. Go look.

7. Sending one email with your resume and cover letter to multiple employers. Whether you put them all in the “to” line or bcc them all, there’s no better way to signal that you’re just mass-mailing your materials out, rather than conducting a customized, targeted job search.

8. Having an unprofessional address. If you like to traverse the Web as “Sexy Mama” or “Partying Paul,” get a different email address for job searching. Addresses like these are so unprofessional that they will trump anything else about your application.

9. Formatting your email like a business letter. When you’re sending business correspondence through postal mail, you should include the date, your address, and the recipient’s address at the top of the letter. However, when you’re emailing someone, there’s no need to include any of that information, and doing so makes you look like you don’t use email much.

10. Using your work account to apply for other jobs. A surprising number of resume submissions come from candidates’ current work email address. If you’re using work time to search for another job, employers will assume you’ll do the same to them.