Today, it's rare that emails are larger than 20MB.
Soon, this will change. Cheap devices that generate high-quality digital video that easily displays on a PC are becoming ubiquitous. An example is the Sony Cyber-shot.
Over the next two years, high-quality video will also be built into mass-market cellphones. This will further extend availability.
Such videos, even in short clips, consume 50MB to 200MB. Consumers will want to email these around. So will businesspeople, for solid business reasons. During 2006 and 2007, mail systems will frequently have to contend with attachments in this range. It will cause many email systems to choke. Email administrators will apply size limits, but they'll be under pressure to significantly expand those limits. Staging in virtual folders will be a common workaround.