SMTP-AUTH and TLS

[Tobias Brink <tobias.brinkNO.SPAM@gmail.com>]

Hello.

I want to send mail via SMTP.  The server in question demands clients
to connect encrypted and authenticate using SMTP-AUTH PLAIN.  The
server refuses unencrypted authentication and refuses to relay mail
from unauthenticated connections.

I have the following in my .gnus.el:

  (setq send-mail-function 'smtpmail-send-it)
  (setq message-send-mail-function 'smtpmail-send-it)
  (setq smtpmail-starttls-credentials
      '(("smtp.myserver.tld" 25 nil nil)))
  (setq smtpmail-default-smtp-server "smtp.myserver.tld")

and something like the following in .authinfo:

  machine smtp.myserver.tld login tobias password secret

From setting `smtpmail-debug-info' and `smtpmail-debug-verb' to `t' I
see that Gnus doesn't even try to use TLS and authenticate (at least I
interpret the following output to mean that):

Sending...
Sending via mail...
220 smtp.myserver.tld ESMTP Postfix
250-smtp.myserver.tld
250-PIPELINING
250-SIZE 10240000
250-VRFY
250-ETRN
250-STARTTLS
250-ENHANCEDSTATUSCODES
250-8BITMIME
250 DSN
250 2.1.0 Ok
554 5.7.1 <someone@someisp.tld>: Relay access denied
221 2.0.0 Bye
smtpmail-send-it: Sending failed; SMTP protocol error

Setting up KMail to use this server works so the error must be in my
Gnus configuration, only I don't know where.

Versions: Gnus 5.11, GNU Emacs 22.1.1

Thanks in advance,
Tobias