Email data in user-defined format.

Email data in user-defined format.

I want unidentified users to be able to email stuff to my database in user-defined format - and it is working fine, to a point. 

I can extract the subject line and body text using ZC_Subject and ZC_Content. But I don't understand how I can find out who sent me the data. I hoped I might be able to use ZC_From, but it didn't collect anything.

Can this be done please?