Ending the Fentanyl Crisis Act of 2019 This bill reduces drug quantity thresholds that trigger certain mandatory minimum prison terms for a defendant who manufactures, distributes, imports, exports, or possesses with intent to distribute fentanyl. Additionally, the bill directs the U.S. Postal Service to increase the availability of chemical screening devices and dedicate the appropriate number of personnel to interdict fentanyl and other substances that are unlawfully imported into the United States.