Earlier quoted context omitted.
It's fairly common for companies to send automated e-mails from a separate domain to try to mitigate the impact of spam filters. ceo@company.com doesn't want her e-mails to be marked as spam just because some marketing e-mails are being sent from noreply@company.com.
And I take it using a separate subdomain wont work either? I.E. if you send mail from hi@marketing.example.com it will still hurt frank@example.com so they need to get a different domain?
[1]: http://www.magillreport.com/Spamhaus-Provides-Answers-Part-F...