Sending email from domain different than primary? Possible? - php

Question

this may be a noobish question. I'd like to know if I can send emails from the server that say, domain1.com is associated with, as coming from domain2.com and also having the origin show as coming from domain2.com?
The reason I'd like to do this, is because I have an application I'm developing and would like to send emails from the domain, for example - maildomain.com instead of coming from domain.com
Emails are being sent with php's mail function.

Answer 1

Yes, you can:
$to = 'nobody#example.com';
$subject = 'the subject';
$message = 'hello';
$headers = 'From: webmaster#example-two.com' . "\r\n" .
'Reply-To: webmaster#example-two.com' . "\r\n" .
'X-Mailer: PHP/' . phpversion();
mail($to, $subject, $message, $headers);
You should set up some things, so the receiver doesn't mark it as spam though:
Set up DNS MX records with low priority for the receiving domain, pointing to sending server
Setup correct reverse DNS entries for sending server
..

Answer 2

The "From" address in an email is entirely arbitrary. As long as you have permission to submit mail to a server's queue, you can put any From address in it that you want. president#whitehouse.gov, julian#wikileaks.org, etc.
To do this with PHP's mail() function, use *$additional_headers*. For example:
$to = "whoever#example.com";
$subject = "This is an example!";
$message = "Hello,\n\nThis is message body.\n\nIsn't that nice?\n\n";
$headers = "From: El Presidente <president#whitehouse.gov>\r\n"
. "X-foo: bar\r\n";
$result = mail($to, $subject, $message, $headers);

Answer 3

Possible? Yes is sure is. See the below example from PHP.net. However, I'm going to put a little piece of fine print here, as I think you might run into some trouble, and I want to make it easier for you in the future. ;) Your current webhost may block this, I've never seen it, but I've heard it can happen. Also, there is a thing called SPF, or Sender Policy Framework, that is a DNS record that you can set to determine what servers can send on your behalf. Many servers that could receive your mail, and especially GMail check for valid SPF. All you have to do is add a TXT record on your name server for domain.com. It should look something like this: v=spf1 mx a:maildomain.com -all. This says any records that have an MX record set up, and the IPs that are resolved from maildomain.com are valid 'non-spam'. Also, you will to fail any other mail origin.
<?php
$to = 'nobody#example.com';
$subject = 'the subject';
$message = 'hello';
$headers = 'From: webmaster#example.com' . "\r\n" .
'Reply-To: webmaster#example.com' . "\r\n" .
'X-Mailer: PHP/' . phpversion();
mail($to, $subject, $message, $headers);
?>

Answer 4

If the mail server is an open mail relay then yes, you can send from a different domain. It is of course seen as a vulnerability as spammers can use it to send out junk mail. The configuration of the mail server to get this functionality depends on its platform but you can usually test a server's ability to freely relay messages by telneting to the server on port 25 and doing an ehlo test.