xref: /curl/docs/examples/smtp-mime.c (revision f540e43b)
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24 
25 /* <DESC>
26  * Send SMTP mime emails
27  * </DESC>
28  */
29 
30 #include <stdio.h>
31 #include <string.h>
32 #include <curl/curl.h>
33 
34 /* This is a simple example showing how to send mime mail using libcurl's SMTP
35  * capabilities. For an example of using the multi interface please see
36  * smtp-multi.c.
37  *
38  * Note that this example requires libcurl 7.56.0 or above.
39  */
40 
41 #define FROM    "<sender@example.org>"
42 #define TO      "<addressee@example.net>"
43 #define CC      "<info@example.org>"
44 
45 static const char *headers_text[] = {
46   "Date: Tue, 22 Aug 2017 14:08:43 +0100",
47   "To: " TO,
48   "From: " FROM " (Example User)",
49   "Cc: " CC " (Another example User)",
50   "Message-ID: <dcd7cb36-11db-487a-9f3a-e652a9458efd@"
51     "rfcpedant.example.org>",
52   "Subject: example sending a MIME-formatted message",
53   NULL
54 };
55 
56 static const char inline_text[] =
57   "This is the inline text message of the email.\r\n"
58   "\r\n"
59   "  It could be a lot of lines that would be displayed in an email\r\n"
60   "viewer that is not able to handle HTML.\r\n";
61 
62 static const char inline_html[] =
63   "<html><body>\r\n"
64   "<p>This is the inline <b>HTML</b> message of the email.</p>"
65   "<br />\r\n"
66   "<p>It could be a lot of HTML data that would be displayed by "
67   "email viewers able to handle HTML.</p>"
68   "</body></html>\r\n";
69 
70 
main(void)71 int main(void)
72 {
73   CURL *curl;
74   CURLcode res = CURLE_OK;
75 
76   curl = curl_easy_init();
77   if(curl) {
78     struct curl_slist *headers = NULL;
79     struct curl_slist *recipients = NULL;
80     struct curl_slist *slist = NULL;
81     curl_mime *mime;
82     curl_mime *alt;
83     curl_mimepart *part;
84     const char **cpp;
85 
86     /* This is the URL for your mailserver */
87     curl_easy_setopt(curl, CURLOPT_URL, "smtp://mail.example.com");
88 
89     /* Note that this option is not strictly required, omitting it results in
90      * libcurl sending the MAIL FROM command with empty sender data. All
91      * autoresponses should have an empty reverse-path, and should be directed
92      * to the address in the reverse-path which triggered them. Otherwise,
93      * they could cause an endless loop. See RFC 5321 Section 4.5.5 for more
94      * details.
95      */
96     curl_easy_setopt(curl, CURLOPT_MAIL_FROM, FROM);
97 
98     /* Add two recipients, in this particular case they correspond to the
99      * To: and Cc: addressees in the header, but they could be any kind of
100      * recipient. */
101     recipients = curl_slist_append(recipients, TO);
102     recipients = curl_slist_append(recipients, CC);
103     curl_easy_setopt(curl, CURLOPT_MAIL_RCPT, recipients);
104 
105     /* allow one of the recipients to fail and still consider it okay */
106     curl_easy_setopt(curl, CURLOPT_MAIL_RCPT_ALLOWFAILS, 1L);
107 
108     /* Build and set the message header list. */
109     for(cpp = headers_text; *cpp; cpp++)
110       headers = curl_slist_append(headers, *cpp);
111     curl_easy_setopt(curl, CURLOPT_HTTPHEADER, headers);
112 
113     /* Build the mime message. */
114     mime = curl_mime_init(curl);
115 
116     /* The inline part is an alternative proposing the html and the text
117        versions of the email. */
118     alt = curl_mime_init(curl);
119 
120     /* HTML message. */
121     part = curl_mime_addpart(alt);
122     curl_mime_data(part, inline_html, CURL_ZERO_TERMINATED);
123     curl_mime_type(part, "text/html");
124 
125     /* Text message. */
126     part = curl_mime_addpart(alt);
127     curl_mime_data(part, inline_text, CURL_ZERO_TERMINATED);
128 
129     /* Create the inline part. */
130     part = curl_mime_addpart(mime);
131     curl_mime_subparts(part, alt);
132     curl_mime_type(part, "multipart/alternative");
133     slist = curl_slist_append(NULL, "Content-Disposition: inline");
134     curl_mime_headers(part, slist, 1);
135 
136     /* Add the current source program as an attachment. */
137     part = curl_mime_addpart(mime);
138     curl_mime_filedata(part, "smtp-mime.c");
139     curl_easy_setopt(curl, CURLOPT_MIMEPOST, mime);
140 
141     /* Send the message */
142     res = curl_easy_perform(curl);
143 
144     /* Check for errors */
145     if(res != CURLE_OK)
146       fprintf(stderr, "curl_easy_perform() failed: %s\n",
147               curl_easy_strerror(res));
148 
149     /* Free lists. */
150     curl_slist_free_all(recipients);
151     curl_slist_free_all(headers);
152 
153     /* curl does not send the QUIT command until you call cleanup, so you
154      * should be able to reuse this connection for additional messages
155      * (setting CURLOPT_MAIL_FROM and CURLOPT_MAIL_RCPT as required, and
156      * calling curl_easy_perform() again. It may not be a good idea to keep
157      * the connection open for a long time though (more than a few minutes may
158      * result in the server timing out the connection), and you do want to
159      * clean up in the end.
160      */
161     curl_easy_cleanup(curl);
162 
163     /* Free multipart message. */
164     curl_mime_free(mime);
165   }
166 
167   return (int)res;
168 }
169