Updated
<?php global $post;
$address_name = str_replace(
',',
'',
get_post_meta( $post->ID, '_mfl_entry_address_name', true )
);
$address_street = str_replace(
',',
'',
get_post_meta( $post->ID, '_mfl_entry_address_street', true )
);
$address_line_2 = str_replace(
',',
'',
get_post_meta( $post->ID, '_mfl_entry_address_line_2', true )
);
$address_line_3 = str_replace(
',',
'',
get_post_meta( $post->ID, '_mfl_entry_address_line_3', true )
);
$address_postcode = str_replace(
',',
'',
get_post_meta( $post->ID, '_mfl_entry_address_postcode', true )
);
$full_address = array(
$address_name,
$address_street,
$address_line_2,
$address_line_3,
$address_postcode
);
$output="";
$glue=",";
foreach($full_address as $value){
if(!empty($value)){
$output .= $value.$glue;
}
}
$output = trim($output, $glue);
echo $output;
?>
Let me know if that works.