Checking the spam or junk email folder is a common first step in troubleshooting missing email issues because sometimes legitimate emails are incorrectly flagged as spam by the email client's filtering system. Once identified as not spam, future emails from the same sender may correctly arrive in the inbox. Changing the theme of the email client or adding a signature won't affect the reception of emails. While creating a new email address might eventually solve the problem, it is not a practical first step as it can cause disruption and loss of historical emails.