Once an e-mail sender is marked as a "junk e-mail" sender, all of their e-mails from that point on will be directed to your "Junk E-mail" folder. If you find a legitimate sender's e-mails are ending up in your Junk folder, it is a relatively simple fix.
1. Right click on the e-mail that was incorrectly identified.
2. Go to -->Junk then click "Not Junk."
3. Click "OK" on the pop up dialogue box.
That's it! All future e-mails from that sender should now go directly to your inbox.