The color indicate the classification of the mail given by SpamDrain.
|Newsletters or marketing emails. This isn't quite spam but instead newsletters, marketing messages and offers from stores and companies you might have had a contact with. You enable and disable the newsletter filter on the User settings page.|
|Without doubt classified as spam.|
|Doubtfully classified as spam.|
|Without doubt classified as valid e-mail.|
|Doubtfully classified as valid e-mail.|
|Virus or phishing e-mail.|