I'm guessing, but would expect short odds on it.
Internally, Fera use distribution lists. Standard practice for corporate email systems, no confidentiality involved when all are employees. If you sent to or cc the distribution list it appears as "Xyz group" every time you see it. Same for anyone else internally. Somebody, office junior or at any rate somebody not familiar with email mechanics, decided an internal style distribution list was ideal for a public emailing in the same way. They made the distribution list, called it "2014 Husbandry Survey" and sent it to the list as the addressee or as a cc. The list name would be all most in the office were aware of.
Their email server translates that into a list of names. The list is always there, but not visible for most users in their internal email client. If the email includes anyone outside then the "not visible" status is lost and all the addresses are in plain text. I'm not calling it "hidden" because it's not very deep, there will be menu options to see it or display the header as text on the internal client. It's just obscured for convenience so most internal users see something like "to: Xyz group" instead of 300 email addresses.
What they should do is use bcc for the distribution list. Then their mail server would have sent separate emails to each address without adding the list to each one. The list stays on the server. Externally, an address or cc list appears as 300 separate addresses because that's all your mail client has. It cannot refer back to the corporate server for a group name because that's not a common standard.
Easy mistake to make. Not the first time, won't be the last. It's an education issue, but nobody gets training for using email. A simple remedy is to stop hiding the distribution lists so it's obvious what's going on. That won't happen because it's how pretty much all corporate email systems are set up whether by employees or contractors, private or public.
