This mod goes in your phpbb forums directory/includes/ucp/ucp_register.php

PHPBBSpammerMod.php

<?php
add before the line:
$message = $message . '<br /><br />' . sprintf($user->lang['RETURN_INDEX'], '<a href="' . append_sid("{$phpbb_root_path}index.$phpEx") . '">', '</a>');

the mod:
				//Suicidolt's SPAM BLOCKER
				$userCheck = file_get_contents("http://www.stopforumspam.com/api?ip=" . $user_row['user_ip'] . "&email=" . $user_row['user_email'] . "&username=" . $user_row['username']);
					//gather output on user from stopforumspam
				if ($userCheck)
				{
					$patt = '@<(([^>\s]+)[^>]*)>(.+)<\/\2>@';	//regex
					preg_match_all($patt, $userCheck, $match, PREG_SET_ORDER);
						//divide up output from stopforumspam, it's xml
					$ip_spam = false;	//initialize variables as false, not a spammer yet
					$email_spam = false;
					$user_spam = false;
					$i = 1;
					foreach($match as $key => $value)
					{
						if ($i == 1 && $key == 1 && $value[3] == "yes")
						{	//ip matched, spammer
							$ip_spam = true;
							$i++;
						}
						else if ($i == 2 && $value[1] == "appears" && $value[3] == "yes")
						{	//email matched, spammer
							$email_spam = true;
							$i++;
						}
						else if ($i == 3 && $value[1] == "appears" && $value[3] == "yes")
						{	//username matched, spammer``
							$user_spam = true;
							$i++;
						}
						else if ($i == 1 && $value[1] == "appears")
						{
							$i++;
						}
						else if ($i == 2 && $value[1] == "appears")
						{
							$i++;
						}
						else if ($i == 3 && $value[1] == "appears")
						{
							$i++;
						}
					}
					/*$emailsplit = explode('.', $user_row['user_email']);
					if ($emailsplit[sizeof($emailsplit) - 1] == 'cn')	//block chinese emails
					{
						$email_spam = true;
					}
					elseif ($emailsplit[sizeof($emailsplit)- 1] == 'ru')	//block russian emails
					{
						$email_spam = true;
					}*/
					/*$emailsplit = explode('@', $user_row['user_email']);
					if (strrpos($emailsplit[1], ".") != stripos($emailsplit[1], "."))
					{	//block emails with more than 1 . after the @
						$email_spam = true;
					}*/
					if ($ip_spam || $email_spam || $user_spam)	//if anything matched
					{
						//include($phpbb_root_path . 'includes/functions_user.' . $phpEx);
							//make sure we have access to ban and delete
						user_ban('ip',$user_row['user_ip'], 0, "", false, "Spammer");	//ban user by ip
						user_delete('remove', $user_id);	//delete user, removing all posts
						//$userCheck = file_get_contents('http://www.stopforumspam.com/add.php?username=' .
						//	urlencode($user_row['username']) . '&ip_addr=' . $user_row['user_ip'] .
						//		'&email=' . urlencode($user_row['user_email']) . '&api_key=');
							//submit the username, email, and ip to stopforumspam
							//if you have an api key, uncomment that call and put in your api key
					}
				}
				else
				{
					user_delete('remove', $user_id);
					trigger_error('Could not check user.  Please register again.', E_USER_WARNING);
				}
				//End SPAM BLOCKER
?>

Does it mean i need to open /includes/ucp/ucp_register.php

and before line:
$message = $message . '<br /><br />' . sprintf($user->lang['RETURN_INDEX'], '<a href="' . append_sid("{$phpbb_root_path}index.$phpEx") . '">', '</a>');

i need to paste code that you mention after your line 5 "the mod:" ? And then i remove last line of the code i pasted ( ?> ) ?

i got allow_url_fopen disabled warning on registration page after adding this code, i think it can be solved by adding
[PATH=/home/userhere/public_html]
allow_url_fopen=on

to the bottom of the global/server php.ini file

I further commented out line: user_ban('ip',$user_row['user_ip'], 0, "", false, "Spammer");
being afraid my ban ip list will grow too much