Setting Your Proxy Server Variable in Emacs

Running your Emacs behind a proxy server

(setq url-proxy-services
   '(("no_proxy" . "^\\(localhost\\|10.*\\)")
     ("http" . "proxy.com:8080")
     ("https" . "proxy.com:8080")))

(setq url-http-proxy-basic-auth-storage
    (list (list "proxy.com:8080"
                (cons "Input your LDAP UID !"
                      (base64-encode-string "LOGIN:PASSWORD")))))

Something else that people have shared over on reddit is the follwing which I have yet to try:

(setq url-proxy-services
      '(("http"     . "http://proxy.example.com:8080")
        ("https"    . "http://proxy.example.com:8080")
	    ("ftp"      . "proxy.example.com:8080")
	    ("no_proxy" . "^.*example.com")))

Source: https://stackoverflow.com/questions/10787087/use-elpa-emacs-behind-a-proxy-requiring-authentication/18697223#18697223