[Skunkworks] Sending mail attachments

Hello skunks, I have a small office with 512/512 Kbps dedicated. Number of users is 6 (not heavy users but send quiet a number of mails per day) Is this bandwidth sufficient to occasionally send files between 5-10MB's? I noted that sending more than 5MB makes outlook on some, especially older computers enter "hung mode" Do I need to have the bandwidth increased? The client is kind of cost conscious. Kindly advice, Jeff