14. The computer readable medium of claim 9 , wherein the instructions further comprise instructions that when executed cause the graymail detection system to: store the extracted features in a database.
9. A non-transitory computer readable medium, on which is stored software for detecting graymail without explicit user feedback, comprising instructions that when executed by a graymail detection system cause the graymail detection system to: receive a non-spam email for a user; extract features of the email; predict with a classifier model based on the extracted features whether the user would consider the email as graymail; modifying the email by inserting tracking information before delivering the email to the user; storing the inserted tracking information in a tracking database; track user actions on the email without explicit user feedback using the inserted tracking information; updating the tracking database upon detection of tracked user actions on the email; determine whether the user considered the email as graymail responsive to the tracked user actions without explicit user feedback; and train the classifier model responsive to the tracked user actions.