net: implementation of SMTP RFC 2821 (#5807)

vlib/net/smtp/smtp_test.v

@@ -0,0 +1,18 @@
+import smtp
+
+fn test_smtp() {
+
+	server := 'smtp.mailtrap.io'
+	port := 2525
+	username := '46d1daf3ff04f'
+	password := '1e8ba2dbf19f4f'
+	subject := 'Hello from V'
+	from := 'dev@vlang.io'
+	to := 'dev@vlang.io'
+	msg := '<h1>Hi,from V module, this message was sent by SMTP!</h1>'
+	body_type := 'html'
+	debug := true //use while debugging
+
+	smtp.send_mail(server, port, username, password, subject, from, to, msg, body_type,
+		debug)
+}