Can't install mailpile


Hello there,
I am trying to install mailpile in accordance with the instructions, but I’m getting an error
Unable to locate package mailpile
I’ve added all repositories correctly…

 deb stretch main
    deb-src stretch main
   deb stretch/updates main
    deb-src stretch/updates main

    # stretch-updates, previously known as 'volatile'
    deb stretch-updates main

    deb release main
    deb-src stretch-updates main

please help…