nixCraft

I am a bit confused about these two. What is the difference between a mail hub and a smart host.

I would also like to know how to setup an smtp server in my office so that I don't need to use the ISP's smtp server. I prefer to use postfix.

ricc

a smart host uses ISP's mail server to send and retrieve mails also known as null mail client. All your lan computer send mail to local mail server and local smart host uses ISP's mail server.


a mail hub is your own linux / unix / windows server running at least smtp / pop3 / imap service. a mail hub is directly connected to internet and sends and retrieves mail without ISP's server. It means your server should be online 24x7x365 days. So that it sits on your LAN, acting as the interface between your users and the Internet.


Is your server connected to internet 24x7? Do you have dedicated IP? If so you can setup Postdfix as smtp server

If you have DHCP based ip... does your isp allows incoming port 25 (most isp block to avoid spam). Also keep in mind that most properly configured mail server will reject your mail as dhcp ip often black listed and used for spam.

Thank you tom,

A good explanation.

I have a dsl connection. Currently we have a business email account from yahoo and use its smtp server for routing email. For now, I would like to know how to set up a smart host. I would also like to setup postfix such that it allows only authorized users. Like for instance we can only use Yahoo's smtp server when we do a username/password authentication. I hope you can understand what I mean.

Also, as you mentioned, I had earlier tried to use a postfix server as a mail hub. But most of the time the receiving server used to say that it is rejected. This brings me to my other question. How do these receiving servers know that my IP is dynamic and not static. And what happens when I opt for a static IP from my ISP and he gives me an IP from the same set of IP's that he has in the dynamic pool.

I apologize for any mistakes and I hope that you all understand what I am saying.

Thanks,
ricc

This is what I use, I don't have yahoo as ISP but local cable isp:

main.cf config:
Replace smtp.isp.com with actual ISP smtp server name. You can also specify port with [smtp.isp.comortNo]

Also leave smtp_sasl_security_options to blank if ISP's smtp using
is plain text auth i.e. it should look as follows:

Open /etc/postfix/saslpasswd and add:
Once again setup username / server and password.

Now configure outlook / and other MUAs to send mail via your server. To get mail from ISP use fetchmail and locally send to mailbox.

A nice tutorial @ 16.*SMTP Authentication for Mail servers

__________________
May the force with you!

Thanks Monk,

I have tried it and it works. My local clients can send email using my SMTP server without authentication.

How do I setup authentication for my SMTP server. Like the authentication mechanism used by the ISPs.

I have seen that email clients can use different types of authentication like : PLAIN; NTLM/SPA ; GSSAPI ; DIGEST-MD5; CRAM-MD5; Login ; and lastly POP before SMTP.

How do we setup our smart-host to use these and allow only authenticated users to use my server. I am just experimenting to better understand how email is transferred.

ricc