Php form don't work

hy there guys!
man, i’m losing my mind with a php form. i mean, it works fine when i set my e-mail, but if i change the e-mail to my client’s one, it stops working!
i’ve checked different e-mails and they all work, except the one it was supose to work for!
any ideas? is there any other way to create forms beside the php form here in kirupa?

thanks in advance