The letter is I

Joyce Hynes to Duane Ibsen
Eric Ibsen to Carl Ihde
Janet Ihde to Aimee Imbrescia
Joseph Imbrescia to D Inc
Gary Ince to Betty Ingersoll
Dan Ingersoll to Marvin Ingraham
Randy Ingraham to Bob Inman
Brian Inman to Catherine Ipsen
Carla Irby to Kevin Irion
L Irion to Hilda Irriger
Albert Irvin to John Irwin
Jolene Irwin to Donna Isakson
E Isakson to Martin Ison
John Isotalo to Dolores Ivers
Bonnie Iversen to Donna Iverson
Doris Iverson to Sheryl Iverson
Terry Iverson to Whitefish I