Merge pull request #14 from shuler/master

Improve disconnect from SMTP server after 10 seconds

checkmail.go

@@ -51,7 +51,7 @@ func ValidateHost(email string) error {
 		return ErrUnresolvableHost
 	}
 
-	client, err := smtp.Dial(fmt.Sprintf("%s:%d", mx[0].Host, 25))
+	client, err := DialTimeout(fmt.Sprintf("%s:%d", mx[0].Host, 25), forceDisconnectAfter)
 	if err != nil {
 		return NewSmtpError(err)
 	}
@@ -75,6 +75,21 @@ func ValidateHost(email string) error {
 	return nil
 }
 
+// DialTimeout returns a new Client connected to an SMTP server at addr.
+// The addr must include a port, as in "mail.example.com:smtp".
+func DialTimeout(addr string, timeout time.Duration) (*smtp.Client, error) {
+	conn, err := net.DialTimeout("tcp", addr, timeout)
+	if err != nil {
+		return nil, err
+	}
+
+	t := time.AfterFunc(timeout, func() { conn.Close() })
+	defer t.Stop()
+
+	host, _, _ := net.SplitHostPort(addr)
+	return smtp.NewClient(conn, host)
+}
+
 func split(email string) (account, host string) {
 	i := strings.LastIndexByte(email, '@')
 	account = email[:i]