office365 smtp auth issue

From: Volker Schmid via curl-library <curl-library_at_lists.haxx.se>
Date: Mon, 25 Sep 2023 15:59:22 +0200

Hi,

we are using libcurl in version 7.71.1 (32 bit) on Windows to send email using SMTP. The login fails to some customers office365.com server. Here is the log. I replaced some sensitive information with xxxxxxx, please apologise.

     CURL: Trying 52.97.201.114:25...
     CURL: Connected to smtp.office365.com (52.97.201.114) port 25 (#0)
     CURL: 220 AM9P195CA0024.outlook.office365.com Microsoft ESMTP MAIL Service ready at Thu, 21 Sep 2023 13:58:47 +0000
     CURL: EHLO XXXXXXXXXX-102
     CURL: 250-AM9P195CA0024.outlook.office365.com Hello [185.173.180.160]
     CURL: 250-SIZE 157286400
     CURL: 250-PIPELINING
     CURL: 250-DSN
     CURL: 250-ENHANCEDSTATUSCODES
     CURL: 250-STARTTLS
     CURL: 250-8BITMIME
     CURL: 250-BINARYMIME
     CURL: 250-CHUNKING
     CURL: 250 SMTPUTF8
     CURL: STARTTLS
     CURL: 220 2.0.0 SMTP server ready
     CURL: EHLO XXXXXXXXXX-102
     CURL: 250-AM9P195CA0024.outlook.office365.com Hello [185.173.xxx.xxx]
     CURL: 250-SIZE 157286400
     CURL: 250-PIPELINING
     CURL: 250-DSN
     CURL: 250-ENHANCEDSTATUSCODES
     CURL: 250-AUTH LOGIN XOAUTH2
     CURL: 250-8BITMIME
     CURL: 250-BINARYMIME
     CURL: 250-CHUNKING
     CURL: 250 SMTPUTF8
     CURL: AUTH LOGIN
     CURL: 334 xxxxxxxxxxxxxxxx
     CURL: xxxxxxxxxxxxxxxxxxxxxx==
     CURL: 334 xxxxxxxxxxxxxxxx
     CURL: xxxxxxxxxxxxxxxxx=
     CURL: Operation timed out after 8002 milliseconds with 0 out of 0 bytes received
     CURL: Closing connection 0
     CURL: schannel: shutting down SSL/TLS connection with smtp.office365.com port 25
     Error performing GET. Curl ec:28
     CURL Error Buffer content: Operation timed out after 8002 milliseconds with 0 out of 0 bytes received

It looks like only AUTH LOGIN XOAUTH2 is supported and the lib is trying AUTH LOGIN. This was answered with silence for > 8 seconds and then timed out.

Is there some flag or option we need to turn on in libcurl to allow SMTP sending through such email server?

I already found the CURLOPT_XOAUTH2_BEARER option, but to be honest I don't know the process to get the values needed. From where do I get a Bearer Token? Do I have to ask the customer on every sending for some token? Or is this some setting the customer enters like a username and I have to save and use it? How does this work?

Thanks!

Volker

-- 
Unsubscribe: https://lists.haxx.se/mailman/listinfo/curl-library
Etiquette:   https://curl.se/mail/etiquette.html

Received on 2023-09-25