Pass a pointer to a zero terminated string as parameter. It will be used to
specify the sender address in a mail when sending an SMTP mail with libcurl.
+An originator email address in SMTP lingo is specified within angle brackets
+(<>) which libcurl will not add for you before version 7.21.4. Failing to
+provide such brackets may cause the server to reject your mail.
+
(Added in 7.20.0)
.IP CURLOPT_MAIL_RCPT
Pass a pointer to a linked list of recipients to pass to the server in your