Here are some tasks you can do in order to prevent emails from a specific sender from going to your junk folder:

1. Locate the email in your junk folder.
2. Mark the email as 'Not Spam'.
3. Add the sender to your ‘safe senders’ list.
4. Check your filters in your email settings and make sure the sender is set as 'never send to junk folder'.
5. Check your email client’s spam settings.
6. Check your email client’s 'Task & Rules' settings.