I have a form that is only returning the last box checked instead of all values that were checked. Please help, i'm pulling my hair out!

html CODE for form:

<!----this is where the Industries check box starts----->



<tr>
<td height="175" colspan="2" align=left valign=top><div style='width:350px;float:left;padding-top:5px;'><b>What best describes your organization? <span style='color:#CC0000;font-size:125%;'></span></b></div>
<br clear=all />
<table width="387">
<tr>
<td width="158"><label>
<input type="checkbox" name="Industries[]" value="Aerospace" id="Aerospace" />
<span class="Checkbox">Aerospace</span></label></td>
<td width="217" class="Checkbox"><input type="checkbox" name="Industries[]" value="Manufacturing" id="Manufacturing" />
Manufacturing</td>
</tr>
<tr>
<td><label>
<input type="checkbox" name="Industries[]" value="Automotive" id="Automotive" />
<span class="Checkbox">Automotive</span></label></td>
<td class="Checkbox"><input type="checkbox" name="Industries[]" value="Mining" id="Mining" />
Mining
</td>
</tr>
<tr>
<td><span class="Checkbox">
<label>
<input type="checkbox" name="Industries[]" value="Chemical" id="Chemical" />
Chemical</label>
</span></td>
<td><span class="Checkbox">
<input type="checkbox" name="Industries[]" value="OilGas" id="OilGas" />
Oil &amp; Gas</span></td>
</tr>
<tr>
<td><span class="Checkbox">
<label>
<input type="checkbox" name="Industries[]" value="Education" id="Education" />
Education</label>
</span></td>
<td><span class="Checkbox">
<input type="checkbox" name="Industries[]" value="Pharmaceutical" id="Pharmaceutical" />
Pharmaceutical</span></td>
</tr>
<tr>
<td><span class="Checkbox">
<label>
<input type="checkbox" name="Industries[]" value="GovernmentFederal" id="GovernmentFederal" />
Government-Federal
</label>
</span></td>
<td><span class="Checkbox">
<input type="checkbox" name="Industries[]" value="Rail" id="Rail" />
Rail</span></td>
</tr>
<tr>
<td><span class="Checkbox">
<label>
<input type="checkbox" name="Industries[]" value="GovernmentMunicipal" id="GovernmentMunicipal" />
Government-Municipal</label></span></td>
<td><span class="Checkbox">
<input type="checkbox" name="Industries[]" value="Utility" id="Utility" />
Utility</span></td>
</tr>
<tr>
<td><span class="Checkbox">
<label>
<input type="checkbox" name="Industries[]" value="GovernmentState" id="GovernmentState" />
Government-State</label>
</span></td>
<td><span class="Checkbox">
<input type="checkbox" name="Industries[]" value="Other" id="Other" />
Other:
<label>
<input name="Other Explanation" type="text" id="OtherExplanation" size="22" />
</label>
</span></td>
</tr>
</table>
<div style='width:380px;float:left;padding-top:5px;'><b><span style='color:#CC0000;font-size:125%;'> </span></b></div>
<br clear=all />
<table width="381">
</table></td>



PHP CODE to process form:

<?php
if(!isset($_POST['submit']))
{
//This page should not be accessed directly. Need to submit the form.
echo "error; you need to submit the form!";
}
$organizationname = $_POST['OrganizationName'];
$firstname = $_POST['FirstName'];
$lastname = $_POST['LastName'];
$businessemail = $_POST['BusinessEmail'];
$industries = $_POST['Industries'];
foreach ( $industries as $industry)
{
$msg .= "$industry\n";
}
$otherexplanation = $_POST['OtherExplanation'];
$newsletter = $_POST['Newsletter'];

//Validate content entered
if(empty($organizationname)||empty($firstname)||em pty($lastname)||empty($businessemail))
{
echo ("Name and email are mandatory. Please go back and try again.");
exit;
}

//validate newsletter has been selected
if(empty($newsletter))
{
echo ("Please make sure you select a newsletter. Go back and try again.");
exit;
}

//Adjust for Magic Quotes
$firstname = stripslashes ($firstname);
$lastname = stripslashes ($lastname);

//Trying to figure our the Arrays function!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!! !!!!!!!


//End of Trying to figure out the Array function!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!! !

$email_from = 'focus@arcadisweb.com';//<== update the email address
$email_subject = "New Focus Newsletter Sign-up";
$msg = "The results from the Focus Newsletter sign up form fields are below. (From arcadisweb.com/focussignup.html) \n\n";
$msg .= "Industry chosen:\n$industry\n\n";

$to = "focus@arcadis-us.com";//<== update the email address
$headers = "From: $email_from \r\n";
//Send the email!
mail($to,$email_subject,$msg,$headers);
//done. redirect to thank-you page.
header ('Location: http://www.arcadisweb.com/Thankyoupage.html');
//Function to validate against any email injection attempts
function IsInjected($str)
{
$injections = array('(\n+)',
'(\r+)',
'(\t+)',
'(%0A+)',
'(%0D+)',
'(%08+)',
'(%09+)'
);
$inject = join('|', $injections);
$inject = "/$inject/i";
if(preg_match($inject,$str))
{
return true;
}
else
{
return false;
}
}
if(IsInjected($visitor_email))
{
echo "Bad email value!";
exit;
}


?>