examples: Updated SMTP examples to set CURLOPT_UPLOAD

docs/examples/simplesmtp.c

@@ -62,6 +62,7 @@ int main(void)
      * as a FILE pointer) as shown here.
      */
     curl_easy_setopt(curl, CURLOPT_READDATA, stdin);
+    curl_easy_setopt(curl, CURLOPT_UPLOAD, 1L);
 
     /* send the message (including headers) */
     res = curl_easy_perform(curl);

docs/examples/smtp-multi.c

@@ -120,6 +120,7 @@ int main(void)
    curl_easy_setopt(curl, CURLOPT_USERNAME, USERNAME);
    curl_easy_setopt(curl, CURLOPT_PASSWORD, PASSWORD);
    curl_easy_setopt(curl, CURLOPT_READFUNCTION, read_callback);
+   curl_easy_setopt(curl, CURLOPT_UPLOAD, 1L);
    curl_easy_setopt(curl, CURLOPT_MAIL_FROM, MAILFROM);
    curl_easy_setopt(curl, CURLOPT_MAIL_RCPT, rcpt_list);
    curl_easy_setopt(curl, CURLOPT_USE_SSL, (long)CURLUSESSL_ALL);

docs/examples/smtp-tls.c

@@ -118,6 +118,7 @@ int main(void)
 
     /* value for envelope reverse-path */
     curl_easy_setopt(curl, CURLOPT_MAIL_FROM, FROM);
+
     /* Add two recipients, in this particular case they correspond to the
      * To: and Cc: addressees in the header, but they could be any kind of
      * recipient. */
@@ -131,6 +132,7 @@ int main(void)
      */
     curl_easy_setopt(curl, CURLOPT_READFUNCTION, payload_source);
     curl_easy_setopt(curl, CURLOPT_READDATA, &upload_ctx);
+    curl_easy_setopt(curl, CURLOPT_UPLOAD, 1L);
 
     /* Since the traffic will be encrypted, it is very useful to turn on debug
      * information within libcurl to see what is happening during the transfer.