Have you ever done a screen capture, pasted it into an email message and hit the send button only to find out later from the flame mail, that the email was huge?  Pretty embarrassing eh?  I just did it a couple of minutes ago because I forgot to turn on automatic image compression.

Huh?  How do you do that?

Well, the default picture quality in Outlook is set to print at 220 ppi.  If you change that setting to email at 96 ppi, you will see a rather huge reduction in the size of those outbound emails.

Here's how:

1. Create a new email message in Outlook.  My default format is HTML.
2. Do a print screen or use the Windows Vista Snipping Tool to copy a picture blob to the clipboard.  In my example here, I did a print screen of my Windows Vista desktop at 1920x1200 resolution.  If I didn't make any changes, the outbound email would be huge.
3. Paste the picture blob into the body of the email message.  Here's what it looks like so far (see below).  There is no apparent way to force the behavior I want.
4. 
5. The key here is to select the image by clicking it with the mouse.  When you do that, you'll notice a dynamic tab will display on the Outlook ribbon bar (see below).
6. 
7. Click the Format tab and you'll notice all kinds of new tasks that can be used against pictures.
8. Click the Compress Picture button in the Adjust group.  This is the first group on the left side of the ribbon.  You'll be presented with the following dialog box.
9. 
10. Do not check the Apply to selected pictures only option.  Instead, click the options button and you are presented with the following dialog box.
11. 
12. Change the default setting from Print to E-mail (96 ppi) and click OK to save changes. 
13. Click Ok to save changes again on the Compress Pictures dialog box.