How can I regain the choice of merely opening/viewing an e-mail photo attachment or downloading it and taking up unnecessary disk space?

Question

Idiot Internet Explorer always gave me the option of merely opening a document or saving it to my hard drive. I thought Firefox was giving me that option also, until I started realizing over the past two or three months - I've been using Firefox since December - that every photo I look at is being downloaded and saved onto my hard drive!
I had zero disk space left to do Internet security updates with last Thursday. Been cleaning out my "Downloads" file. Most of the stuff I didn't even choose to download. It's just being saved in the file automatically.

Answer 1

If the files are loose inside the iPhoto library package here's one way to get them out:
1 - open your library, select all of the photos in the library and add a unique keyword, XXXX,  to all of them.
2 - Rebuild the library with  iPhoto Library Manager  as follows:
Using iPhoto Library Manager  to Rebuild Your iPhoto Library
1 - download iPhoto Library Manager and launch.>Click on the Add Library button,
2 -  select the library you want to add from those in the selection window.
3 - make sure that in the rebuild window the checkbox  "Scavange orphaned photos" is checked.
4 - now that the library is listed in the left hand pane of iPLM, click on your library and go to the Library ➙ Rebuild Library menu option
5 - in the next  window name the new library and select the location you want it to be placed. Click on the Create button.
Note 1: This creates a new library based on the LIbraryData.xml file in the library and will recover Events, Albums, keywords, titles and comments. However, books, calendars, cards and slideshows will be lost.
Note 2:  Your current library will be left untouched for further attempts at a fix if so desired.
3 - open the library, create a smart album with the criterial "Keyword is not XXXX".
4 - the smart album will include those photos that were not visible in your original library. Select them and use the key combination of Command+Option+Delete to move them to the iPhoto Trash bin.
5 - empty the iPhoto Trash bin via the iPhoto ➙ Empty iPhoto Trash Bin menu option.
6 - empty the Trash bin in the Dock to remove the files from your hard drive completely.
Be sure to read Note 1 above.  You can use the new library without your books, slideshow, etc. and it will not  contain those errant files.  Of course delete the original library if the new one is satisfactory.