On release 1.1.1,it seems to have a bug on email notification.
To delete mail from email_table table, you test the result of mail
function.
If true, you delete the record from the database. But on Unix and
sendmail, php function mail() always return false and the mail is
sended but not deleted from the database, so after, all mails are
ended when you modify a bug.

file : email_api.php
On line 796 :
if ( !$mail->Send() ) {
$t_success = false;
} else {
$t_success = true;
if ( $t_email_data->email_id > 0 ) {
email_queue_delete( $t_email_data->email_id );
}
}

I have deleted this test and it's running on Unix.
We are running on PHP 4.3.11