$sent = mail($to, $subject, $name, $dropin_refreshments, $befriend, $stuffing, $seminar, $registration, $steward, $outreach, $ethnic, $pre-retirement, $mobility, $writing, $deputy, $new_group, $research, $equipment, $headers) ;
This can not work.
[man]mail[/man]
takes usually only 4 arguments:
$sent = mail($to, $subject, $message, $headers);
So, you should make one message out of all those variables.
<?php
$to = "webcoordinator@sheffieldu3a.org.uk";
$subject = "New Members questionnaire";
$email = $_REQUEST['email'] ;
// all these should put into one $message
$name = $_REQUEST['name'] ;
$dropin_refreshments = $_REQUEST['dropin_refreshments'] ;
$befriend = $_REQUEST['befriend'] ;
$stuffing = $_REQUEST['stuffing'] ;
$seminar = $_REQUEST['seminar'] ;
$registration = $_REQUEST['registration'] ;
$steward = $_REQUEST['steward'] ;
$outreach = $_REQUEST['outreach'] ;
$ethnic = $_REQUEST['ethnic'] ;
$pre-retirement = $_REQUEST['pre-retirement'] ;
$mobility = $_REQUEST['mobility'] ;
$writing = $_REQUEST['writing'] ;
$deputy = $_REQUEST['deputy'] ;
$new_group = $_REQUEST['new_group'] ;
$research = $_REQUEST['research'] ;
$equipment = $_REQUEST['equipment'] ;
$headers = "From: $email";
$sent = mail($to, $subject, $message, $headers) ;
if($sent)
{print "Your form was sent successfully"; }
else
{print "We encountered an error sending your form"; }
?>