Refactor Client struct for better readability and organization

Reordered and grouped fields in the Client struct for clarity. The reorganization separates logical groups of fields, making it easier to understand and maintain the code. This includes proper grouping of TLS parameters, DSN options, and debug settings.

smtp/smtp.go

@@ -37,28 +37,45 @@ import (
 
 // A Client represents a client connection to an SMTP server.
 type Client struct {
-	// Text is the textproto.Conn used by the Client. It is exported to allow for
+	// Text is the textproto.Conn used by the Client. It is exported to allow for clients to add extensions.
-	// clients to add extensions.
 	Text *textproto.Conn
-	// keep a reference to the connection so it can be used to create a TLS
+
-	// connection later
+	// auth supported auth mechanisms
+	auth []string
+
+	// keep a reference to the connection so it can be used to create a TLS connection later
 	conn net.Conn
-	// whether the Client is using TLS
+
-	tls        bool
+	// debug logging is enabled
-	serverName string
+	debug bool
-	// map of supported extensions
+
+	// didHello indicates whether we've said HELO/EHLO
+	didHello bool
+
+	// dsnmrtype defines the mail return option in case DSN is enabled
+	dsnmrtype string
+
+	// dsnrntype defines the recipient notify option in case DSN is enabled
+	dsnrntype string
+
+	// ext is a map of supported extensions
 	ext map[string]string
-	// supported auth mechanisms
+
-	auth       []string
+	// helloError is the error from the hello
-	localName  string // the name to use in HELO/EHLO
+	helloError error
-	didHello   bool   // whether we've said HELO/EHLO
+
-	helloError error  // the error from the hello
+	// localName is the name to use in HELO/EHLO
-	// debug logging
+	localName string // the name to use in HELO/EHLO
-	debug  bool       // debug logging is enabled
+
-	logger log.Logger // logger will be used for debug logging
+	// logger will be used for debug logging
-	// DSN support
+	logger log.Logger
-	dsnmrtype string // dsnmrtype defines the mail return option in case DSN is enabled
+
-	dsnrntype string // dsnrntype defines the recipient notify option in case DSN is enabled
+	// tls indicates whether the Client is using TLS
+	tls bool
+
+	// serverName denotes the name of the server to which the application will connect. Used for
+	// identification and routing.
+	serverName string
 }
 
 // Dial returns a new [Client] connected to an SMTP server at addr.