First of all, I'm sorry that I'm asking so many questions on this article but now I've started the project, I'm determined to successfully complete it. Section 11 - Page 5 - To see if SMTP-AUTH and TLS work properly now run the following command: [root@HostBlade ~]# telnet localhost 25 Trying 127.0.0.1... Connected to localhost. Escape character is '^]'. 220 HostBlade.example.com ESMTP Exim 4.66 Sat, 14 Jul 2007 18:29:05 +0100 ehlo something 250-HostBlade.example.com Hello localhost [127.0.0.1] 250-SIZE 52428800 250-PIPELINING 250-STARTTLS 250 HELP As you can see, my result is slightly different although I don't think it is a problem as it may be because instead of postfix and dovecot, I am using exim and dovecot and will also be adding Teapop once I sorted this out. Finally, on to my actual question - The thing that concerns me is that I don't get the: 250-AUTH LOGIN PLAIN Is this essential or optional? Could this cause potentail problems if it is not there?