Why can't I post images on this group? Are you mean?

[Joseph Dunphy]

Answer: Because there are 5 million users of Stumbleupon, and the
files section of a googlegroup only has 100 MB worth of space. That
might sound like a lot, but as a modest sized photo can easily weigh
in at .25 Meg or more, 100 MB translates into 400 photos or less.
While I obviously don't expect to see anything approaching a
membership of 5 million, even a small ripple in a pool that deep is
going to look like a tidal wave from the perspective of this little
group. One has to put some limitations on the use of the resources of
this group if they are to last.

But there is an affiliated group at Flickr where you can post your
images, as long as they are suitable for general audiences

http://www.flickr.com/groups/stumbleupon/

If you don't already have a membership at Flickr, getting one might be
worth considering. While I won't deny that Yahoo does provide the
occasional headache, and concerns have been expressed about the
upcoming universal profile, you get unlimited storage space, an
impressive uploading limit, you can blog your images and it is a very
reliable host.

You might run into a few trolls and flamers in the forums, but name a
site where that isn't a problem. If you approach this site with a
reasonable level of caution (disabling commenting on your photos might
be wise), I think that you might find that it meets your needs in this
area admirably.