id	summary	reporter	owner	description	type	status	priority	milestone	component	version	resolution	keywords	cc	uname	nginx_version
2566	mail_proxy_module proxy_smtp_auth not respecting AUTH capabilities of backend	smoebody@…		"When nginx is proxying smtp auth it always uses ""AUTH PLAIN <base64-encoded-username-and-passsword>"" when trying to authenticate, despite the backend only offers ""AUTH LOGIN"".

This is the traffic between nginx and the backend:
{{{#!bash
220 exchange-backend Microsoft ESMTP MAIL Service ready at Mon, 20 Nov 2023 12:15:10 +0100
EHLO localhost
250-exchange-backend Hello [10.0.0.11]
250-SIZE 37748736
250-PIPELINING
250-DSN
250-ENHANCEDSTATUSCODES
250-AUTH LOGIN
250-8BITMIME
250-BINARYMIME
250-CHUNKING
250 SMTPUTF8
AUTH PLAIN dGVzdAAxMjM0Cg==
504 5.7.4 Unrecognized authentication type
}}}"	defect	closed	minor		nginx-module	1.22.x	invalid			Linux localhost 6.1.0-13-amd64 #1 SMP PREEMPT_DYNAMIC Debian 6.1.55-1 (2023-09-29) x86_64 GNU/Linux	"nginx version: nginx/1.22.1
built with OpenSSL 3.0.8 7 Feb 2023 (running with OpenSSL 3.0.11 19 Sep 2023)
TLS SNI support enabled
configure arguments: --with-cc-opt='-g -O2 -ffile-prefix-map=/build/nginx-AoTv4W/nginx-1.22.1=. -fstack-protector-strong -Wformat -Werror=format-security -fPIC -Wdate-time -D_FORTIFY_SOURCE=2' --with-ld-opt='-Wl,-z,relro -Wl,-z,now -fPIC' --prefix=/usr/share/nginx --conf-path=/etc/nginx/nginx.conf --http-log-path=/var/log/nginx/access.log --error-log-path=stderr --lock-path=/var/lock/nginx.lock --pid-path=/run/nginx.pid --modules-path=/usr/lib/nginx/modules --http-client-body-temp-path=/var/lib/nginx/body --http-fastcgi-temp-path=/var/lib/nginx/fastcgi --http-proxy-temp-path=/var/lib/nginx/proxy --http-scgi-temp-path=/var/lib/nginx/scgi --http-uwsgi-temp-path=/var/lib/nginx/uwsgi --with-compat --with-debug --with-pcre-jit --with-http_ssl_module --with-http_stub_status_module --with-http_realip_module --with-http_auth_request_module --with-http_v2_module --with-http_dav_module --with-http_slice_module --with-threads --with-http_addition_module --with-http_flv_module --with-http_gunzip_module --with-http_gzip_static_module --with-http_mp4_module --with-http_random_index_module --with-http_secure_link_module --with-http_sub_module --with-mail_ssl_module --with-stream_ssl_module --with-stream_ssl_preread_module --with-stream_realip_module --with-http_geoip_module=dynamic --with-http_image_filter_module=dynamic --with-http_perl_module=dynamic --with-http_xslt_module=dynamic --with-mail=dynamic --with-stream=dynamic --with-stream_geoip_module=dynamic"