Stop php mail being marked as spam + regular expression job

Hi, I need to stop emails from a site on my server being marked as spam. Just need someone to make the changes to one php file so the emails sent do not get marked as spam and go into peoples spam or junk boxes. I also need someone that is good with regular expression to modify one search for me so it grabs a few certain pieces of data from a html file. Easy job for someone, my budget for this is $30 and need it done within a few hours idealy. Thanks.