receive mail from public SMTP
 

I have setup a postfix mail server on Mandrake 8.2. I can send out message to public mail like hotmail.com. However, I cannot reply and receive any mail from outside.

What kind of public email service should I register in the internet into to receive mail relay from internet world ?

It depends on the type of connection that you have. If you have a permanent connection, then you need to update your MX record on your DNS server to point to you "mailhub" machine. This would make your mail server destination for anything sent to you. Of course, this assumes you have a domain name registered.

If you simply have a dial up connection (or no domain, or to keep it really simple), then you really don't need to use postfix. In this case just set up your mail program (netscape mail, kmail, whatever) to use the pop server and smtp server that you were given by your ISP.

I hope that helps.

since I want to host the mail server by my local linux machine, how could I update my MX record in DNS server ( my DNS ? or DNS in ISP ? )

If I have just registered those free public Domain Name Sevices like no-ip.com, Can I receive my email from other internet SMTP mail relay host ?

If you have your own DNS server, that is the master for your domain then make the change there. Otherwise the update will occur at no-ip.com. Basically, wherever the "world" looks to find the ip address of your domain that is what will need to be updated.

Let me explain...no there is too much, let me sum up.

I have a cable modem that is always on. My ISP is nice enough to never kick me off, so I've had the same IP address for the last ~6 mos. I registered my domain (somedomain.com) with NameSecure. When I set up my mail server I asked them to update my MX record and point it to www.mydomain.com (they didn't have any online way to do it, but some do). The jist is that mail sent to mydomain.com needs to actually go to an actual machine. If mail was sent to www.mydomain.com then the MX record would be unnecessary, but this is bush league. By pointing the MX to www.mydomain.com anything sent to person@mydomain.com will acually go to the server (presumably www.mydomain.com).

BTW, this took me a while to find out and much google searching. Your needs may be different than mine, but some creative google searches will likely produce some informative sites.

No I don't think it's a DNS or ISP issue. Theoretically, you should be able to access mail on your Linux mail server from another client machine, even if you'll have to use IP address to point to the right host.

I believe it's something of the configuration of TCP/IP wrappers or mail server (whether Postfix or Sendmail). I have not figured that out.

If you happen to know how to make it work, please kindly share it with us.