UNIX for Dummies Questions & Answers

Hi peeps,

I want to learn how to configure mail servers, I am in private network, I am running debian 4.0, practically I have tried courier-mta, courier-imap, postfix, and sendmail.
sometimes I am able to send mail and not able to connect to my imap server which is localhost, sometimes I am able to connect to imap but not able to send mail, etc.
I dont have a domain name and i could not have it. So my question is "is it neccessary to have a domain name to configure mail server? I know i cant recieve mails from internet coz of that.
I am doing this because i want to learn things grounds up. I mean if I am able to do this in home net than i can go on doing this on a static ip and a domain name.
but for the sac of practicing and time being, is there any way to do it ??? I have configured dns on the same machine with a fake and unique domain name which nobody else on the internet have.
I think it will be a good idea for peoples who like to write articles on Howtos and guides.
I am not asking you to spoon feed me, I am asking this because I am confused. I have read and tried a lot of things in very small amount of time,
because of that the information stored in my mind is not linked properly.
so it would be great if you could just clear up things a bit for me.

any links to tutorials will be appriciated.
Thanks for reading my ramblings

I don't know your configuration so it's hard to troubleshoot the problem. What sorts of errors are you receiving when you can't log in to your imap server and what errors are you receiving when you are not able to send mail. Your server logs should have details on what the problem is.

For sendmail and other MTA's, there may be a few issues to consider.

1. Your ISP may be blocking port 25 for all but their own mail servers. It doesn't sound like that's your problem since it seems to be working some of the time.

2. Due to spam, other MTA's will check to see if you have a valid domain and will automatically reject your mail if your IP is not matched to a host name.

3. Again, due to spam, other MTA's automatically block e-mail from general user space such as the Comcast range. Per Comcast (and this is an example; your ISP may have different policies), you're not allowed to run servers on your home cable connection. Since Comcast doesn't block server ports at their firewall, you can get away with it but your mail may be generally blocked.

Why can't you get a domain though? There are lots available at pretty cheap prices. You can hit http://www.dyndns.com to register and manage a DHCP IP address. Their DNS servers accept input from your server as to its true IP and will reconfigure the IP for your domain to point to your server again. It's pretty quick. I used it until I started using a colocated server.

As to your request for howto's, a very fast google search turned up:

Linux Home Server HOWTO

You might want to consider searching for the information next time. Try searching on "howto +sendmail". In this case, that was one of the first items that popped up. It doesn't have imap info but I'm sure another seach would turn up an informative howto.

Carl