7
I searched several sites and google, but there’s always something with PHP or HTML. How to send an email using only C?
1 answer
11
You can use the Curl library if you want to send emails via SMTP.
Follow an example taken from their own website:
#include <stdio.h>
#include <string.h>
#include <curl/curl.h>
int main(void)
{
CURL *curl;
CURLcode res;
struct curl_slist *recipients = NULL;
/* value for envelope reverse-path */
static const char *from = "<[email protected]>";
/* this becomes the envelope forward-path */
static const char *to = "<[email protected]>";
curl = curl_easy_init();
if(curl) {
/* this is the URL for your mailserver - you can also use an smtps:// URL
* here */
curl_easy_setopt(curl, CURLOPT_URL, "smtp://mail.example.net.");
/* Note that this option isn't strictly required, omitting it will result in
* libcurl will sent the MAIL FROM command with no 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);
/* Note that the CURLOPT_MAIL_RCPT takes a list, not a char array. */
recipients = curl_slist_append(recipients, to);
curl_easy_setopt(curl, CURLOPT_MAIL_RCPT, recipients);
/* You provide the payload (headers and the body of the message) as the
* "data" element. There are two choices, either:
* - provide a callback function and specify the function name using the
* CURLOPT_READFUNCTION option; or
* - just provide a FILE pointer that can be used to read the data from.
* The easiest case is just to read from standard input, (which is available
* 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);
/* Check for errors */
if(res != CURLE_OK)
fprintf(stderr, "curl_easy_perform() failed: %s\n",
curl_easy_strerror(res));
/* free the list of recipients */
curl_slist_free_all(recipients);
/* curl won't send the QUIT command until you call cleanup, so you should be
* able to re-use 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 very 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);
}
return 0;
}
Example link: http://curl.haxx.se/libcurl/c/simplesmtp.html
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Cool. I’d also like to see an answer that doesn’t have a dependency on Curl. I hope someone posts something.
– Maniero
You will always have dependency on one library or another. There are no functions in the library boss of the C to do this. Even to open a socket you need a library, or use OS routines and lose portability.
– C. E. Gesser
You can even do it using socket, but there is already a complete implementation of the SMTP protocol, which is not worth doing if you just want to send an email.
– WoLfulus