| Avoiding Spam | Blocking Images | Blocking Email Addresses |
Many of the images sent by email are Web-based graphics, which are files that are downloaded to your computer when you open the message. Using Yahoo! Mail you can block these images, preventing them from being downloaded. If you open the message, you’ll see the text, but you won’t see the images.
Blocking images is a good idea for several reasons:
If you’re sure that the images in a particular message are safe, you can choose to see them for that specific message.
Note that even with image blocking enabled, some images can still appear in your email. These include:

(More Details)
In the upper-right corner of your Yahoo! Mail page, click the Options link, then select Mail Options from the menu.

Tip: You can also go directly to the Spam options
page by clicking the Options link in a message
with blocked images.
The Mail Options page opens.
Click the Spam link on the left.

The spam options open on the right side of the page.
To the right of Block images, select one of the blocking options for incoming images:

Always show images, except in Spam folder—When you open a message in the Spam folder, none of the images that the message contains are downloaded. Images in all other messages are automatically downloaded when you open the messages.
Show images only from my contacts and certified senders—When you open a message from someone in your Yahoo! Contacts or from a certified sender, the images are downloaded.
Initially block all images—When you open a message, none of the images that it contains are downloaded. This is the default setting.
Click the Save Changes button to save your settings.

When you’ve enabled image blocking and you open an email containing Web-based images, a message appears above the email informing you that Yahoo! Mail has blocked images. To see the blocked images, click the Show Images link. The images display in that email only. All other Web-based images in other emails continue to be blocked.
You can disable most image blocking at any time by repeating the steps above and then selecting the Always show images, except in Spam folder option.