add vendoring

vendor/gitlab.com/etke.cc/go/trysmtp/README.md

@@ -0,0 +1,20 @@
+# trySMTP
+
+Library that tries to connect to SMTP host by TO/target email address:
+
+* Lookup MX and A
+* Try to connect to SMTP on different ports
+* Try to use STARTTLS if server supports it
+* Return SMTP Client with `Mail()` and `Rcpt()` already called
+
+
+```go
+from := "sender@example.com"
+to := "target@example.org"
+client, err := trysmtp.Connect(from, to)
+if err != nil {
+	// something went wrong!
+}
+
+client.Data([]byte("your email data here"))
+```