2008-12-28 22:53:33 H=localhost (***.***.***.***) [127.0.0.1] F=<firstname.lastname@example.org> rejected RCPT <email@example.com>: "Your IP: 127.0.0.1 : Your domain domain.com is not allowed in header From"
1. If you use webmail and you get the error mentioned above then your domain is not pointed to our server in local DNS and "Always accept mails locally" option is not set. This applies mainly to Email only hosting clients and those who use Google Apps and this can be fixed through Cpanel:
Login to your cpanel > in Mail section click on MX editor > set "Always accept mails locally" to Yes.
2. If you use php script then most probably you are trying to send message from a domain which is not hosted on our server. E.g. you have feedback form on your site where php script tries to send message as from user's email (firstname.lastname@example.org
In this case the error can be fixed by using your hosted domain in "from" field and by setting safe_mode to "Off" . Also we recommend you to add 'reply to' header to the message, which will allow you reply to your users.