Emails of prominent or known to be generally racist police departments:

Philadelphia: police.public_affairs@phila.gov

Springfield, Illinois: CommunicationsDirector@cwlp.com

Milwaukee: mpdnews@milwaukee.gov

Los Angeles: contact.lapdonline@gmail.com

Jackson, Mississippi: JPDChief@jacksonms.gov

Birmingham: BPDSuggestions@birminghamal.go

Links to send messages to other prominent police departments: 

Baltimore: https://www.baltimorepolice.org/baltimore-police-department-general-inquires

NYPD: https://www1.nyc.gov/site/nypd/about/about-nypd/email-the-commissioner.page