email form - works on windows server - not on linux

[aled]

I have created an email form which works on a windows platform - however i cannot make it work on a linux server. The php must be executing because it redirects to the thankyou.htm page (which I did using a header:location). However - the email is not reaching it's target:

 

Linux Server details:

 

SMTP: localhost

sendmail_from: no value

sendmail_path: /usr/sbin/sendmail -t -i

register_globals: off

 

CODE FOR XHTML and PHP (contactemailform.php) below:

 

XHTML CODE:

 

<form id="form" class="contact_form" method="post" action="contactemailform.php" onsubmit="return validate_form(this);">

<p>

email: (this bit must be filled in)

<br />

<input name="email" type="text" class="input" />

<br />

name:<br /> <input name="subject" type="text" class="input" />

<br />

telephone:

<br />

<input name="telephone" type="text" class="input" />

<br />

message:

<br />

<textarea name="message" rows="7" cols="30" class="input"></textarea>

<br />

<br />

<input type="submit" class="submit" value="submit email" />

</p>

</form>

 

PHP CODE

 

<?php

function spamcheck($field)

  {

//eregi() performs a case insensitive regular expression match

  if(eregi("to:",$field) || eregi("cc:",$field))

    {

    return TRUE;

    }

  else

    {

    return FALSE;

    }

  }//if "email" is filled out, send email

if (isset($_REQUEST['email']))

  {

  //check if the email address is invalid

  $mailcheck = spamcheck($_REQUEST['email']);

  if ($mailcheck==TRUE)

    {

    echo "Invalid input";

    }

  else

    {

    //send email

    $email = $_REQUEST['email'] ;

    $subject = $_REQUEST['subject'] ;

    $message = $_REQUEST['message'] ;

    ini_set("sendmail_path", "/usr/sbin/sendmail -t -i");

    mail("[email protected]", "Subject: $subject",

    $message, "From: $email" );

    header( "Location: http://www.dinky-diggers.com/thankyou.htm" );}

  }

else

//if "email" is not filled out, display the form

  {

  echo "<form method='post' action='mailform.php'>

  Email: <input name='email' type='text' /><br />

  Subject: <input name='subject' type='text' /><br />

  Message:<br />

  <textarea name='message' rows='15' cols='40'>

  </textarea><br />

  <input type='submit' />

  </form>";

  }

?>