No anonymous authentication?

[lmcd]

I'm using an SMTP server that doesn't require authentication, though when Swift-SMTP attempts to authenticate with empty credentials, it fails.

I'm having no issues at all sending mail anonymously with the swaks tool.

How do I specify a credential-less SMTP configuration?

[sbeitzel]

Hmm. According to RFC 4954, if a client is providing an empty user name, the server must deny the authentication request. So, instead of using EHLO the anonymous connection should probably start with HELO.

[wnagrodzki]

If no authentication is required, client should not send AUTH command at all. I was able to send email via telnet with SMTP server that does not require authentication, listing below:

~ % telnet <redacted> 209
Trying <redacted>...
Connected to <redacted>.
Escape character is '^]'.
220 <redacted> Microsoft ESMTP MAIL Service ready at Tue, 4 Jan 2022 12:36:55 +0100
EHLO
250-<redacted> Hello <redacted>
250-SIZE 104857600
250-PIPELINING
250-DSN
250-ENHANCEDSTATUSCODES
250-STARTTLS
250-X-ANONYMOUSTLS
250-AUTH NTLM
250-X-EXPS GSSAPI NTLM
250-8BITMIME
250-BINARYMIME
250-CHUNKING
250-XEXCH50
250-SMTPUTF8
250 XRDST
MAIL FROM:<redacted>
250 2.1.0 Sender OK
RCPT TO:<redacted>
250 2.1.5 Recipient OK
DATA
354 Start mail input; end with <CRLF>.<CRLF>
Subject: My Subject 

Email message.

.
250 2.6.0 <redacted> [InternalId=47369194308060, Hostname=<redacted>] 1085 bytes in 38.911, 0,027 KB/sec Queued mail for delivery

[sbeitzel]

The issue seems to be in SMTPSocket.init(...) -- specifically, the last two lines always try to authenticate, even if the server's response does not actually include a 250-AUTH line:

        let authMethod = try getAuthMethod(authMethods: authMethods, serverOptions: serverOptions, hostname: hostname)
        try login(authMethod: authMethod, email: email, password: password)