Lena,
data: doesn't consume storage where the 1 GB free limit is.
Interesting point. I wonder if that gives Mark a motive to detect the use of data: and treat it as if it had been cid:, at least for the purpose of storage.
The user's subscription control for max attachment size is about the metering or other download restrictions some users may face, particularly on mobile devices. And for that purpose I think it would be more useful if Mark did detect data: and apply the same restrictions.
Shal
Shal Farley