How to delete email message with libcurl and POP3?

Question

Is it possible to do? I know about custom request; so I send custom request with text "DELE", and set message ID that I want to delete. As a result, curl_easy_perform hangs until timeout appears. On web forums people write advice to send also "QUIT" command after "DELE"; but how can I send "QUIT" command if libcurl hangs?

libcurl debug output follows:

* Connected to pop-mail.outlook.com (157.55.1.215) port 995 (#2)
* SSL connection using DES-CBC3-SHA
* Server certificate:
*        subject: C=US; ST=Washington; L=Redmond; O=Microsoft Corporation; CN=*.
hotmail.com
*        start date: 2013-04-24 20:35:09 GMT
*        expire date: 2016-04-24 20:35:09 GMT
*        issuer: C=BE; O=GlobalSign nv-sa; CN=GlobalSign Organization Validation
 CA - G2
*        SSL certificate verify result: unable to get local issuer certificate (
20), continuing anyway.
< +OK DUB0-POP132 POP3 server ready
> CAPA
< -ERR unrecognized command
> USER ************@hotmail.com
< +OK password required
> PASS ******************
< +OK mailbox has 1 messages
> DELE 1
< +OK message deleted
* Operation too slow. Less than 1000 bytes/sec transferred the last 10 seconds
> QUIT
* Operation too slow. Less than 1000 bytes/sec transferred the last 10 seconds
* Closing connection 2

So, the message is removed, but libcurl hangs until speed limit forces it to disconnect, which is bad idea. How to force it to stop after deleting of message and don't wait until timeout comes?

Answer 1

If you look at the libcurl documentation, CURLOPT_CUSTOMREQUEST says:

POP3

When you tell libcurl to use a custom request it will behave like a LIST or RETR command was sent where it expects data to be returned by the server. As such CURLOPT_NOBODY should be used when specifying commands such as DELE and NOOP for example.

That is why libcurl is hanging - it is waiting for more data that the server is not actually sending. So add CURLOPT_NOBODY to stop that waiting.

Answer 2

There's a recently added example code on the libcurl site showing exactly how to do this:

pop3-dele.c