smtp/smtp: add MTA documentation

Readme.md

@@ -226,15 +226,15 @@ client.send(message, (err, message) => {
         related     // an array of attachments that you want to be related to the parent attachment
     }
 
-## new smtp.SMTPConnection(options)
+## new smtp.SMTPConnection(options={})
 
     // options is an object with the following keys
     options =
     {
     	user 		// username for logging into smtp
     	password // password for logging into smtp
-    	host		// smtp host
-    	port		// smtp port (if null a standard port number will be used)
+    	host		// smtp host (defaults to 'localhost')
+    	port		// smtp port (defaults to 25)
     	ssl		// boolean or object {key, ca, cert} (if true or object, ssl connection will be made)
     	tls		// boolean or object (if true or object, starttls will be initiated)
     	timeout	// max number of milliseconds to wait for smtp responses (defaults to 5000)
@@ -243,6 +243,8 @@ client.send(message, (err, message) => {
     	logger // override the built-in logger (useful for e.g. Azure Function Apps, where console.log doesn't work)
     }
 
+To target a Message Transfer Agent (MTA), omit all options.
+
 ## smtp.SMTPConnection#authentication
 
 associative array of currently supported SMTP authentication mechanisms

smtp/smtp.ts

@@ -116,7 +116,9 @@ export class SMTPConnection extends EventEmitter {
 	protected port: number;
 
 	/**
-	 * SMTP class written using python's (2.7) smtplib.py as a base
+	 * SMTP class written using python's (2.7) smtplib.py as a base.
+	 *
+	 * To target a Message Transfer Agent (MTA), omit all options.
 	 */
 	constructor({
 		timeout,