Hello , i'm using a simple php mail() function . it work very well except that , users from hotmail receive this msg : The sender of this message could not be verified by Sender ID. Learn more about Sender ID. NOTE: Hotmail has disabled some of the content of this message for your protection (more information). Enable all message content (once) | Never disable content from this sender any one know how to fix this problem ? this is the code : (removed all tests ... )