The ability to create filters for spam messages in Gmail can sometimes lead to filtering e-mail from real friends.
Besides going "filter happy" on your spam messages, Gmail may accidentally mark a friend's e-mail as spam simply because it mentions certain phrases or products. For situations like these, you can add a whitelist to your Gmail. This will help messages from people you know land in the inbox, and not the trash can.
Step 1: Log in to your Gmail account.
Step 2: Click on the Settings cog in the top-right corner and go to Mail settings.… Read more