smtp-mime.c
/***************************************************************************
* _ _ ____ _
* Project ___| | | | _ \| |
* / __| | | | |_) | |
* | (__| |_| | _ <| |___
* \___|\___/|_| \_\_____|
*
* Copyright (C) Daniel Stenberg, <daniel@haxx.se>, et al.
*
* This software is licensed as described in the file COPYING, which
* you should have received as part of this distribution. The terms
* are also available at https://curl.se/docs/copyright.html.
*
* You may opt to use, copy, modify, merge, publish, distribute and/or sell
* copies of the Software, and permit persons to whom the Software is
* furnished to do so, under the terms of the COPYING file.
*
* This software is distributed on an "AS IS" basis, WITHOUT WARRANTY OF ANY
* KIND, either express or implied.
*
* SPDX-License-Identifier: curl
*
***************************************************************************/
/* <DESC>
* Send SMTP mime emails
* </DESC>
*/
#include <stdio.h>
#include <string.h>
#include <curl/curl.h>
/* This is a simple example showing how to send mime mail using libcurl's SMTP
* capabilities. For an example of using the multi interface please see
* smtp-multi.c.
*
* Note that this example requires libcurl 7.56.0 or above.
*/
#define FROM "<sender@example.org>"
#define TO "<addressee@example.net>"
#define CC "<info@example.org>"
static const char *headers_text[] = {
"Date: Tue, 22 Aug 2017 14:08:43 +0100",
"To: " TO,
"From: " FROM " (Example User)",
"Cc: " CC " (Another example User)",
"Message-ID: <dcd7cb36-11db-487a-9f3a-e652a9458efd@"
"rfcpedant.example.org>",
"Subject: example sending a MIME-formatted message",
NULL
};
static const char inline_text[] =
"This is the inline text message of the email.\r\n"
"\r\n"
" It could be a lot of lines that would be displayed in an email\r\n"
"viewer that is not able to handle HTML.\r\n";
static const char inline_html[] =
"<html><body>\r\n"
"<p>This is the inline <b>HTML</b> message of the email.</p>"
"<br />\r\n"
"<p>It could be a lot of HTML data that would be displayed by "
"email viewers able to handle HTML.</p>"
"</body></html>\r\n";
int main(void)
{
CURL *curl;
CURLcode res = CURLE_OK;
curl = curl_easy_init();
if(curl) {
struct curl_slist *headers = NULL;
struct curl_slist *recipients = NULL;
struct curl_slist *slist = NULL;
curl_mime *mime;
curl_mime *alt;
curl_mimepart *part;
const char **cpp;
/* This is the URL for your mailserver */
curl_easy_setopt(curl, CURLOPT_URL, "smtp://mail.example.com");
/* Note that this option is not strictly required, omitting it results in
* libcurl sending the MAIL FROM command with empty sender data. All
* autoresponses should have an empty reverse-path, and should be directed
* to the address in the reverse-path which triggered them. Otherwise,
* they could cause an endless loop. See RFC 5321 Section 4.5.5 for more
* details.
*/
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. */
recipients = curl_slist_append(recipients, TO);
recipients = curl_slist_append(recipients, CC);
curl_easy_setopt(curl, CURLOPT_MAIL_RCPT, recipients);
/* allow one of the recipients to fail and still consider it okay */
curl_easy_setopt(curl, CURLOPT_MAIL_RCPT_ALLOWFAILS, 1L);
/* Build and set the message header list. */
for(cpp = headers_text; *cpp; cpp++)
headers = curl_slist_append(headers, *cpp);
curl_easy_setopt(curl, CURLOPT_HTTPHEADER, headers);
/* Build the mime message. */
mime = curl_mime_init(curl);
/* The inline part is an alternative proposing the html and the text
versions of the email. */
alt = curl_mime_init(curl);
/* HTML message. */
part = curl_mime_addpart(alt);
curl_mime_data(part, inline_html, CURL_ZERO_TERMINATED);
curl_mime_type(part, "text/html");
/* Text message. */
part = curl_mime_addpart(alt);
curl_mime_data(part, inline_text, CURL_ZERO_TERMINATED);
/* Create the inline part. */
part = curl_mime_addpart(mime);
curl_mime_subparts(part, alt);
curl_mime_type(part, "multipart/alternative");
slist = curl_slist_append(NULL, "Content-Disposition: inline");
curl_mime_headers(part, slist, 1);
/* Add the current source program as an attachment. */
part = curl_mime_addpart(mime);
curl_mime_filedata(part, "smtp-mime.c");
curl_easy_setopt(curl, CURLOPT_MIMEPOST, mime);
/* Send the message */
res = curl_easy_perform(curl);
/* Check for errors */
if(res != CURLE_OK)
fprintf(stderr, "curl_easy_perform() failed: %s\n",
curl_easy_strerror(res));
/* Free lists. */
curl_slist_free_all(recipients);
curl_slist_free_all(headers);
/* curl does not send the QUIT command until you call cleanup, so you
* should be able to reuse this connection for additional messages
* (setting CURLOPT_MAIL_FROM and CURLOPT_MAIL_RCPT as required, and
* calling curl_easy_perform() again. It may not be a good idea to keep
* the connection open for a long time though (more than a few minutes may
* result in the server timing out the connection), and you do want to
* clean up in the end.
*/
curl_easy_cleanup(curl);
/* Free multipart message. */
curl_mime_free(mime);
}
return (int)res;
}
Notice
This source code example is simplified and ignores return
codes and error checks to a large extent. We do this to highlight the libcurl
function calls and related options and reduce unrelated code.
A real-world application will of course properly check every return value and exit correctly at the first serious error.