What is your mailing address/phone number? 3Rivers PO Box 2573 Fort Wayne, IN 46801-2573 260.490.8328 800.825.3641 You can also contact us online. Have more questions? Submit a request 0 Comments Article is closed for comments. Related articles Mailing Address Home Office Address What are your branch locations and hours? What is 3Rivers routing number? What are my sign-on ID and password for the new mobile app?