Anyway, I'm sure everyone has received e-mails in their inbox that have graphics intergrated into them.
Only when I allow them. Microsoft Outlook by default (with spam prevention) is going to block those images from showing.
HTML Email is a somewhat risky proposition these days due to all the restrictions in place because of email spam. Many have their HTML email turned off so they won't get to see the graphics. What they may end up with is a message that has a bunch of attachments which contain the graphics used in the email.
HTML Email is also a major security risk, especially over the past 6 months. Many new exploits are being taken advantage of and opening one of those HTML emails without protection in place could cause damage to your system.
So, be careful!
If you are doing email campaigns, you'll most likely have software available to you that allows you to send both text based and html based email. If the user does not have html email setup, they will see the text version and vice versa.