Originally posted by btmiller
There should be more info in the bounce you got on gmail, but if your hostname does not resolve correctly, that is very likely the source of your problem. You might want to check with no-ip.com to make sure everything is set up correctly. Also, if you have access to a remote machine, you can telnet to port 25 on your host and test your mail server by directly issuing SMTP commands (there are numerous sites on the WWW that explain how to do this).
Unfortunately, gmail only has that much information given to me.
Anyway, after some googling again, I chanced upon our own forum thread
and boy how informative this thread is for email server starters.
From that thread, I concluded that the following steps are what I need to do in order to get my Postfix Email Server up in a LAN.
1) Installed and configured Postfix to send and receive mails locally.
Right now I can only send mail but could not receive. I suspect that my ISP is blocking port 25. But since I have decided to implement this Email Server on a LAN, I suppose I need not care about my ISP blocking port 25?
2) Because I do not have an DNS server in my small
LAN, the next best alternative is to manually add the hostname.domain.com to my windows and linux clients' host file?
3) Installed and run Courier-IMAP so that my email clients can connect using Evolution/Outlook etc. Do I need to configure Courier-IMAP or Postfix to be able to use this IMAP service?
4) As I am not installing mysql, I suppose I need to create real unix accounts in my Linux Email Server in order to add new user for my Postfix Server?
5) Is it necessary to have the follow lines in main.cf? I suppose it is needed only if you specify a different directory right?
command_directory = /usr/sbin
config_directory = /etc/postfix
daemon_directory = /usr/libexec/postfix
queue_directory = /var/spool/postfix