Have you been checking your spam filter and folder? Many of us don’t. We take for granted that the filter’s working correctly—protecting you from unwanted email and leaving your inbox filled with messages that you want to see. We all know that sometimes your spam filter mistakes spam for legitimate emails and allows them into your inbox. But do you also know that sometimes your spam filter mistakes legitimate emails for spam, and filters them out of your inbox?

To determine what’s spam and what’s legitimate, spam filters analyze all parts of the email. They check the email against many different criteria. They also consider, for example, whether the email seems like a “bulk message,” and whether it contains links and graphics. Unfortunately, your legitimate emails sending out your resume can easily get caught in these filters. And legitimate emails from prospective employers, recruiters, job boards, and others can also be trapped.

So while you’re wondering why you’ve received no responses—even automated ones from resumes you’ve submitted through an employer’s online job bank—those responses might be languishing in your spam filter. At least for 30 days, after which they might be automatically deleted without you ever knowing they were there. Or perhaps your email is the one languishing in the employer’s email filter.

Once you start your job search, make a point of checking through your spam folder at least once a day, and consider white-listing (or adding to your address book) job search messages that are inadvertently caught by your hardworking spam filter.

You can get a sense of how spam filters by visiting The Apache SpamAssassin Project.