Help with FaceBook Email to Post feature

Hello Masters

Hope you all are fine.

Well, I have an application where a script will send email with an image attached to the facebook email addresses of the customers (who have opted in). Generally, its done using an special email address that facebook provides like

[some_code_here]@m.facebook.com

Now - if I send an email with attachment to this email address, it works perfect. However, when PHP sends email (via the web application) then only the text is shown and no image is posted / uploaded.

Please help me !

Thanks
ZH