Recently there have been a number of instances where people within the University have sent emails containing large attachments to discussion lists: in one case the attachment was around 150MB in size. The more addresses a large email is sent to, and the larger the attachment, the greater the impact on the email system. In this particular case, the University's main email system ground to a halt and steps had to be taken to remove the email from the system.
Email attachments sent to a discussion list or a group of addresses where the attachment is not required by all recipients is a waste of resources: unless deleted by the recipient the recipient's mailbox grows taking up space on hard disks or servers.
Under discussion is a proposal to limit the size of attachments to emails going to discussion lists, or blocking attachments altogether and providing an alternative means for making files that would otherwise be attached to emails available (like the Division's Public Documents facility).