reflect security = ... in docs and print warning if used

docs/docs/configuration/server.rst

@@ -157,7 +157,7 @@ also can moderate (=activate or delete) comments. Don't forget to configure
     password =
     host = localhost
     port = 465
-    ssl = on
+    security = ssl
     to =
     from =
 
@@ -174,10 +174,10 @@ host
 port
     SMTP port
 
-ssl
-    use SSL to connect to the server. Python probably does not validate the
-    certificate. Needs research, though. But you should use a dedicated
-    email account anyways.
+security
+    use a secure connection to the server, possible values: *none*, *starttls*
+    or *ssl*. Python 2.X probably does not validate certificates (needs
+    research). But you should use a dedicated email account anyways.
 
 to
     recipient address, e.g. your email address

docs/example.conf

@@ -80,10 +80,10 @@ host = localhost
 # SMTP port
 port = 465
 
-# use SSL to connect to the server. Python probably does not validate the
-# certificate. Needs research, though. But you should use a dedicated email
-# account anyways.
-ssl = on
+# use a secure connection to the server, possible values: "none", "starttls"
+# or "ssl". Python 2.X probably does not validate certificates (needs
+# research). But you should use a dedicated email account anyways.
+security = ssl
 
 # recipient address, e.g. your email address
 to =

isso/core.py

@@ -148,6 +148,8 @@ class Config:
                 logger.warn("no such option: [%s] %s", *item)
                 if item in (("server", "host"), ("server", "port")):
                     logger.warn("use `listen = http://$host:$port` instead")
+                if item == ("smtp", "ssl"):
+                    logger.warn("use `security = none | starttls | ssl` instead")
 
         if rv.get("smtp", "username") and not rv.get("general", "notify"):
             logger.warn(("SMTP is no longer enabled by default, add "