Forum: RForum process_mails and determining forums

Hello,

I am trying to input emails into my forums using script/process_mails. 
The mailbox file that I am trying to read from was one that was 
re-created from external data sources. It lacks some header information 
but I would still like to use this data with rforum. My issue is that 
when I run process_mails I get the error:

(unknown error): #<RuntimeError: mail for unknown forum recieved (nil)>

I have updated the forum table within my database to set the list 
address to the address of the from: field in the header. From looking 
around I see that

find_by_list_address

is being called to determine the forum, but what field in the mail 
header is it looking for? The to? My main issue is that the mbox that I 
am trying to read from lacks a to address, and when I manually put one 
into the mail file, process_mails errors out more.