In a Windows 10 machine I'm using a tool (Netwrix Service Monitor) with a SMTP notification feature that doesn't support authentication, so I'm using Stunnel 5.72 as a local relay for SMTP2GO (smtp2go.com), with this configuration:
[smtp2go] client = yes accept = 127.0.0.1:25 connect = mail.smtp2go.com:2525 protocol = smtp protocolAuthentication = plain protocolHost = cloud.mydomain.com protocolUsername = smtp2go@mydomain.com protocolPassword = P@ssw0rd debug = 7
I try both PLAIN and LOGIN as authentication mode, with this is error:
LOGIN: " ... TLS connected: new session negotiated TLSv1.3 ciphersuite: TLS_AES_256_GCM_SHA384 (256-bit encryption) Peer temporary key: X25519, 253 bits Compression: null, expansion: null -> HELO cloud.mydomain.com <- 250 mail.smtp2go.com Hello cloud.mydomain.com [x.x.x.x] -> AUTH LOGIN <- 503 AUTH command used when not advertised Remote server does not support LOGIN authentication ... "
PLAIN: " ... TLS connected: new session negotiated TLSv1.3 ciphersuite: TLS_AES_256_GCM_SHA384 (256-bit encryption) Peer temporary key: X25519, 253 bits Compression: null, expansion: null -> HELO cloud.mydomain.com <- 250 mail.smtp2go.com Hello cloud.mydomain.com [x.x.x.x] -> AUTH PLAIN ******************************************** <- 503 AUTH command used when not advertised PLAIN Authentication Failed Connection reset: 0 byte(s) sent to TLS, 0 byte(s) sent to socket Deallocating application specific data for session connect address ... "
Can anyone help me solve this problem? Thanks!
On Sat, Apr 06, 2024 at 06:35:35AM -0000, Ducale Ducale wrote:
In a Windows 10 machine I'm using a tool (Netwrix Service Monitor) with a SMTP notification feature that doesn't support authentication, so I'm using Stunnel 5.72 as a local relay for SMTP2GO (smtp2go.com), with this configuration:
[snip]
I try both PLAIN and LOGIN as authentication mode, with this is error:
LOGIN: " ... TLS connected: new session negotiated TLSv1.3 ciphersuite: TLS_AES_256_GCM_SHA384 (256-bit encryption) Peer temporary key: X25519, 253 bits Compression: null, expansion: null -> HELO cloud.mydomain.com <- 250 mail.smtp2go.com Hello cloud.mydomain.com [x.x.x.x] -> AUTH LOGIN <- 503 AUTH command used when not advertised Remote server does not support LOGIN authentication ... "
PLAIN:
[snip]
Can anyone help me solve this problem? Thanks!
Hi,
So it seems that the SMTP server is being pedantic, and it seems to require a client to ask for extended SMTP features before actually using them.
I think the attached patch should fix the problem; it at least gets me a bit further with mail.smtp2go.com - it gets me to the "let's verify the credentials you sent" phase.
G'luck, Peter
On 4/9/24 01:31, Peter Pentchev wrote:
So it seems that the SMTP server is being pedantic, and it seems to require a client to ask for extended SMTP features before actually using them.
Merged. See stunnel-5.73b1 on https://www.stunnel.org/downloads.html.
Thank you, Peter.
Best regards, Mike
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Ducale Ducale -
Michał Trojnara -
Peter Pentchev