Exchange 5.5 file attachments size

There are several places to set limits on the size of emails going out (not attachment size) On the IMC properties page, general tab is message size (with service pack 3 and up this can be broken into inbound and outbound size with a registry hack). For individual mailboxes, click on the Limits tab, there are two setting in the lower right corner for inbound and out bound. Plus on the MTA properties page you can limit message size. (did i miss any?)
Hope this helps, let me know if you have any questions.