Parsing a tab delimited log file

(I'm reposting this as it didn't seem to take the first time. If it's a dupe, I apologize.) Hey all. I'm attempting to count the number of unique message IDs from a Microsoft Exchange 2000 tracking log. While the code below works, it takes forever to run. Running through a 16mb log file takes like 10 minutes. If anyone could suggest a better way of doing this, that would be great. Also, below the PHP code, is an example of an Exchange tracking log (Which is tab delimited). Thanks in advance for the help. John Here is the code I'm using: <? ini_set("max_execution_time", 1200); $filename="20031025.log"; $file=file($filename, "r"); $count=count($file); $array=array(); //first 6 lines of the log are header and empty lines $i=5; while ($i<=$count) { $line=explode("\t",$file[$i]); //the MSGID is always the ninth entry in the array $data=$line[9]; //Exchange puts a blank line between each entry in the log file, this creates an empty entry in the array if (!empty($data)) { if (!in_array ($data, $array)) $array[]=$data; } $i++; } $arraycount=count($array); echo $arraycount,"<BR>"; ?> Here is an example of the Exchange tracking logs: 2003-10-26 0:0:35 GMT 10.0.0.1 file-server - Exchange-Server 10.0.0.50 user@domain.com 1019 Exchange-Server0123456789@Exchange-Server.domain.com 0 0 799 1 2003-10-26 0:0:35 GMT 0 Version: 5.0.2195.5329 - - recipient@domain.com - 2003-10-26 0:0:35 GMT 10.0.0.1 file-server - Exchange-Server 10.0.0.50 user@domain.com 1025 Exchange-Server0123456789@Exchange-Server.domain.com 0 0 799 1 2003-10-26 0:0:35 GMT 0 Version: 5.0.2195.5329 - - recipient@domain.com - 2003-10-26 10:13:43 GMT - - - Exchange-Server - recipient@yahoo.com 1020 uniquemessageIDgeneratedbyexchange001002003@Exchange-Server.domain.com 0 0 952 1 2003-10-26 10:13:42 GMT 0 - - - sender@domain.com - 2003-10-26 10:13:43 GMT - - SMTP-Server Exchange-Server - recipient@yahoo.com 1031 uniquemessageIDgeneratedbyexchange001002003@Exchange-Server.domain.com 0 0 952 1 2003-10-26 10:13:42 GMT 0 - - - sender@domain.com - 2003-10-26 0:45:59 GMT 192.168.1.2 SMTP-Server.domain.com - Exchange-Server 10.0.0.50 user@domain.com 1019 Exchange-Server009800500200@Exchange-Server.domain.com 0 0 15188 1 2003-10-26 0:45:59 GMT 0 Version: 95.5329 - - postmaster@domain.com - 2003-10-26 0:45:59 GMT 192.168.1.2 SMTP-Server.domain.com - Exchange-Server 10.0.0.50 user@domain.com 1025 Exchange-Server009800500200@Exchange-Server.domain.com 0 0 15188 1 2003-10-26 0:45:59 GMT 0 Version: 95.5329 - - postmaster@domain.com -