There are many other things that come into my life every day that I can choose to keep or trash. People's advice, for example. Seems everyone has an opinion about everything and are always happy to offer their two cents worth. It's important in those moments to listen for Wisdom speaking. Choose to only keep what is worth keeping and trash the "junk mail". Good advice will always line up with the Heart of God/Word of God.
Spiritual guidance is also another big 'keep or trash' in life. Just like my junk mail, it's amazing the sheer volume of it that finds its way into my 'mailbox'. And none of it is worth keeping. I go to a community festival, and a girl is reading tarot cards. I go on social media and see advertisements for daily horoscopes. I talk to people throughout my day, and hear them promote mystical ideas, things based on human wisdom, not God's. They all seem so inviting and draw you in, much like my junk mail tries to do. But all of it is lifeless and a trap for anyone who welcomes such 'mail' into their lives.
There is actually only one Letter that is worth keeping in life. The Love Letter of God, our Father: the Bible. It's our great Compass. It tells us who God is, who we are, and how we can know Him. It gives perfect advice and spot on spiritual guidance. It's the only Letter we need and the only Letter worth opening. All the rest is just a bunch of junk mail.