Am 18.10.2025 um 20:11 schrieb SherwoodP via curl-library
<[email protected]>:
BACKGROUND:
I am trying to use curl v8.6.0 on a Windows 11 system to send email to my POP3 server
(att.com). AT&T uses "secure mail keys" for authentication.
I can access AT&T's email web interface using a user name and password.
I can also access the same account with Eudora, which requires a secure mail
key.
USING CURL:
This is the curl C++20 code I am using to send a sample message:
curl = curl_easy_init();
if (curl)
{
CURLcode code=curl_easy_setopt(curl, CURLOPT_URL, si .server);
code=curl_easy_setopt(curl, CURLOPT_USE_SSL, (long ) CURLUSESSL_ALL );
code = curl_easy_setopt(curl, CURLOPT_SSL_VERIFYPEER, 0L); // Tell libcurl to
*not* verify the peer
code = curl_easy_setopt(curl, CURLOPT_USERNAME, si .userName);
code = curl_easy_setopt(curl, CURLOPT_PASSWORD, si .pw);
code = curl_easy_setopt(curl, CURLOPT_MAIL_FROM, si .from);
recipients = curl_slist_append(recipients, si .to);
if (strlen( si .cc)) // cc: is optional
recipients = curl_slist_append(recipients, si .cc);
code = curl_easy_setopt(curl, CURLOPT_MAIL_RCPT, recipients);
code = curl_easy_setopt(curl, CURLOPT_READFUNCTION, payload_source);
code = curl_easy_setopt(curl, CURLOPT_READDATA, &upload_ctx);
code = curl_easy_setopt(curl, CURLOPT_VERBOSE, 1L);
/* send the message (including headers) */
res = curl_easy_perform(curl);
}
Structure si at the beginning of the code above contains
si{
server = "smtp://outbound.att.net:587"
userName = "MyUserName"
pw = "MySecureKey"
t = "ToEmailAddr"
from = "FromEmailAddr"
cc = "<[email protected]>"
messageID = "Communicate_000000006334"
subject = "Communicate test email"
nBodyLines = 10
body
[0] = "\tThe Germ"
[1] = ""
[2] = "A mighty creature is the germ,"
[3] = "Though smaller than a pachyderm."
[4] = "His customary dwelling place"
[5] = "Is deep within the human race."
[6] = "His childish pride he often pleases"
[7] = "By giving people strange diseases."
[8] = "Do you, my poppet, feel infirm?"
[9] = "You probably contain a germ."
};
Running this code gives res = CURLE_WEIRD_SERVER_REPLY (8) "curl_easy_perform() failed: Weird server
reply" if I use the AT&T secure key as si.pw, and "Login denied" if I use the AT&T
password.
To debug my usage of curl, I'd like to know what the "weird reply" is, or any
other logging that curl provides. If the curl code is wrong in any way, or missing some
detail of authentication, I'd appreciate advice on how to fix it.
For comparison, the email client Eudora can successfully send email to this
account. An excerpt from Eudora's debugging log is below. This shows that
Eudora has successfully logged in.
MAIN 16:14.54 Preparing messages to Send: 1
MAIN 16:14.54 RSET
MAIN 16:14.54 MAIL FROM:<FromEmailAddr>
MAIN 16:14.54 RCPT TO:<ToEmailAddr>
MAIN 16:14.54 DATA
MAIN 16:14.54 Test message
MAIN 16:14.54 Preparing messages to Send: 0
21296 16:14.54 Open 67.195.12.35:465
21296 32:14.54 Sent: " 16 03 01 00 F4 01 00 00 F0 03 03 C5 93 55 57 E6"
...
21296 64:14.54 Rcvd: " 16 03 03 13 2E 02 00"
...
21296 64:14.54 Rcvd: "220 smtp.mail.yahoo.com ESMTP ready\r\n"
21296 32:14.54 Sent: "EHLO MyComputerName.MyEmailDomain\r\n"
21296 64:14.54 Rcvd: "250-hermes--production-gq1-6b8576c5cf-gs5mr Hello
MyComputerName.MyEmailDomain [xx.xx.xx.xx])\r\n"
21296 64:14.54 Rcvd: "250-PIPELINING\r\n"
21296 64:14.54 Rcvd: "250-ENHANCEDSTATUSCODES\r\n"
21296 64:14.54 Rcvd: "250-8BITMIME\r\n"
21296 64:14.54 Rcvd: "250-SIZE 41697280\r\n"
21296 64:14.54 Rcvd: "250 AUTH PLAIN LOGIN XOAUTH2 OAUTHBEARER\r\n"
21296 32:14.54 Sent: "AUTH LOGIN\r\n"
21296 64:14.54 Rcvd: "334 xxxxxxxxxxxx\r\n"
21296 32:14.54 Sent: "xxxxxxxxxxxxxxxxxxxxxxxxxxxx\r\n"
21296 64:14.54 Rcvd: "334 xxxxxxxxxxxx\r\n"
21296 32:14.54 Sent: "xxxxxxxxxxxxxxxxxxxxxxxx\r\n"
21296 64:14.56 Rcvd: "235 2.7.0 Authentication successful\r\n"
21296 32:14.56 Sent: "RSET\r\n"
21296 64:14.56 Rcvd: "250 2.0.0 OK\r\n"
21296 32:14.56 Sent: "MAIL FROM:<FromEmailAddr>\r\n"
21296 64:14.56 Rcvd: "250 2.1.0 Sender <FromEmailAddr> OK\r\n"
21296 32:14.56 Sent: "RCPT TO:<ToEmailAddr>\r\n"
21296 64:14.56 Rcvd: "250 2.1.5 Recipient <ToEmailAddr> OK\r\n"
21296 32:14.56 Sent: "DATA\r\n"
21296 64:14.56 Rcvd: "354 Ok Send data ending with <CRLF>.<CRLF>\r\n"
21296 32:14.56 Sent: "X-Mailer: QUALCOMM Windows Eudora Version 7.1.0.9\r\n"
21296 32:14.56 Sent: "Date: Sat, 18 Oct 2025 10:53:07 -0700\r\n"
21296 32:14.56 Sent: "To: ToEmailAddr\r\n"
21296 32:14.56 Sent: "From: FromEmailAddr\r\n"
21296 32:14.56 Sent: "Subject: Test message\r\n"
21296 32:14.56 Sent: "Mime-Version: 1.0\r\n"
21296 32:14.56 Sent: "Content-Type: text/plain; charset="us-ascii";
format=flowed\r\n"
21296 32:14.56 Sent: "\r\n"
21296 32:14.56 Sent: "Body of message.\r\n"
21296 32:14.56 Sent: "\r\n"
21296 32:14.56 Sent: ".\r\n"
21296 64:14.57 Rcvd: "250 OK , completed\r\n"
21296 32:14.57 Sent: "QUIT\r\n"
21296 64:14.57 Rcvd: "221 Service Closing transmission\r\n"
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