Since the email module does not allow attachments, the best way I can think of to send multiple photos to multiple friends via the Ning platform:
1. Create a Photo Album
2. Add the photos you wish to send at one time, to the Album.
3. After you have saved the Album, go to that Album from: Photos/My Albums
4. You have to look for it, but there is a SHARE button (it's an envelope right below Edit and Delete Album)
5.This takes you to a screen where you can send to friends. It allows you to enter email addresses, or select from friend list.

I have NOT tested this yet, was just asked the question. It may just send a link to your Album slide show. But, even so, this is a great, clean way to share photos with friends or colleagues - - no uploading and downloading for them.