Thank you for being a valued part of the CNET community. As of December 1, 2020, the forums are in read-only format. In early 2021, CNET Forums will no longer be available. We are grateful for the participation and advice you have provided to one another over the years.

Thanks,

CNET Support

General discussion

IP address question

May 22, 2008 1:41PM PDT

Is the ip address that was given to you by your internet service provider different from the ip address of your domain name hosted by a server? If I send an email using a mail server, what is the ip address that the recepient will see? A mail server has it's own IP right?

Discussion is locked

- Collapse -
Internal and External IP
May 22, 2008 2:17PM PDT

If you are within the network, like at home, every computer has its own IP address. So your server at home could be 192.168.1.10, your laptop could be 192.168.1.11 and your desktop could be 192.168.1.12. If you go to a website like gatebot.com on all three computers, it shows you ONE IP Address... the external one from your ISP. So if you were trying to access any one of those computers from the outside world, you would type in that one IP address and from there you could be routed to any one of those computers using ports.

Back to your question, the recipient will most likely see the ISP IP address (the external one) or the domain name pointing/associated with it.

Also, if the server hosting your website is not in your network, your ISP's IP address will differ from your domain name / server.

~Sovereign

- Collapse -
Yes...
May 22, 2008 2:19PM PDT

Unless you are running the server over the connection provided by your ISP, the IP addresses are indeed different. The IP address in the e-mail, though, depends on how the mail server is set up. Traditionally it would report the IP address of the computer used to send the e-mail, followed by that of the e-mail server in the full headers. Alternatively though, it can be configured to report its own IP address as the original sender, omitting yours from the headers, which is what is done with most anonymous e-mail services. Thus, the IPs are different, but you don't know which one you get unless you know how its set up or send yourself a test e-mail and see what's listed.

John

- Collapse -
response
May 23, 2008 6:29AM PDT

Thanks for the response guys, is it really automatic that it's your mail server that will be seen by the recipient? I check some headers of our email, I am not sure but i think it's the ip of our domain that has been sent.

- Collapse -
Yes, but...
May 23, 2008 7:09AM PDT

By 'default' your e-mail server's IP address will be included in the headers, but most e-mail server setups will also display the IP address of the computer that sent the e-mail in the first place. Remember to check the full headers, not just the 'standard' (abbreviated) headers.

John

- Collapse -
response
May 25, 2008 1:42PM PDT

thanks for the response guys, I did a forward dns on one of our domain, the ip result of that forward dns and the ip of the header from our email is the same.


From info@domain.ph Wed May 21 01:02:57 2008
Return-Path: <nobody@host.company.com>
Authentication-Results: mta684.mail.mud.domain.com from=domain.ph; domainkeys=neutral (no sig)
Received: from (edited ip- 00.00.00.00) (EHLO host.company.com) (ip numbers)
by mta684.mail.mud.domain with SMTP; Wed, 21 May 2008 02:02:32 -0700
Received: from nobody by host.company.com with local (Exim)
for email@domain.com; Wed, 21 May 2008 10:02:57 +0200

So what is the ip in the header of our email ? Is that the i.p of our domain or our mail server?
Is it possible that the ip of a domain and the mail server the same numbers?

- Collapse -
Working from the ground up...
May 27, 2008 3:59AM PDT

The order of progression is typically:

Received: Receiver's mail server
Received: Sender's mail server
Received: Sender's computer

Though there can be additional lines representing spam filters, redirection, etc.

If you do an ipconfig (or ifconfig with OS X/Linux) from the command prompt/terminal on the computer you're using to send the e-mail you can find out if the sender's IP address is actually included. (It's not possible to say for sure given the redacted headers and no internal knowledge.) Any other IP addresses would be the mail server(s).

John