While our Mozilla Mail tutorial focuses on Windows, keep in mind that Mozilla Mail is a "cross-platform" email client: it runs and operates the same way on Windows, Apple's Mac OS X and Linux.
The Mozilla Foundation also offers the standalone Thunderbird email client: see the Mozilla Thunderbird Tutorial
Spam and Junk Mail in Mozilla Mail or SeaMonkey Mail
Mozilla Mail comes with built-in junk mail filters. Moreover, Mozilla Mail's filters are "adaptative"; in other words, they learn. When junk mail isn't filtered as such, you can manually tell Mozilla Mail that this email should have been marked as spam.
When Mozilla Mail tags an email as junk, you will see this notice when the email is selected. If it was mistakenly filtered as junk, click the Not Junk button. With time, Mozilla Mail will learn with good accuracy which emails you want to keep.
J Mark email as "junk mail"
Shift+J Mark email as "not junk"
Rich Email Content and Junk Mail Filtering in Mozilla Mail
Email providers increasingly protect you from rich content, images for examples. It is technically easy to create a "dynamic image", i.e. an image which transfers information to the server merely by being referenced in an email. For example, a spammer can use such an image to determine whether your email address is active or not. (See below for a few more details.)
Mozilla Mail's Junk Mail Controls
Mozilla Mail comes with smart spam fighting capabilities, and has an entire utility devoted to junk mail, the Junk Mail Controls. To launch the Junk Mail Controls utility, go to Tools > Junk Mail Controls.
From the Junk Mail Controls dialog, you will find general configuration settings, such as telling Mozilla Mail to trust any sender in your address book, or how to handle emails filtered as junk, or choose disable junk mail controls altogether.
Mozilla Mail Junk Mail Controls 
Since no junk mail filter is infallible, we recommend that you do not choose to automatically move to the trash emails Mozilla Mail perceives as junk.
It is worth taking the time to manually delete your junk emails after review. Most customers whose emails remain unanswered will take it personally.
However, telling Mozilla Mail to delete emails you manually mark as spam is a great time saver:
Since Mozilla Mail's junk mail filters are "adaptative", they can be trained by your actions: every time you click the Junk button for an email, you help Mozilla Mail become more accurate in its predictions.
- JUNK MAIL AND LINKED CONTENT -
goodGuys.com/logo.gif is a static, harmless way to reference an image in an email/web page.
badGuys.com/logo.php?q=john@email.com is a sneaky way to determine that the image was successfully requested by the owner of this email address - thus that the email address is active.
(Note that we are not revealing anything new here.)
The above also applies to clickable links in the body of your emails: clicking on www.badGuys.com?q=john@email.com could have the exact same effect and server script behind it.
www.badGuys.com?q=X56XAD5765SD (or any similar looking gibberish) could too.
Bottom line: do not bother opening suspicious looking emails you were not expecting to receive. Even an email appearing as coming from PayPal or Amazon.com could be a fraud.
If you have added PayPal or Amazon to your safe list, and an email from them is caught as spam, trust your junk mail filters, the email is probably a fake.


Email Clients Tutorials
Mozilla Mail Tutorial