Classifying Emails into Human vs Machine Category

It is an essential product requirement of Yahoo Mail to distinguish between personal and machine-generated emails. The old production classifier in Yahoo Mail was based on a simple logistic regression model. That model was trained by aggregating features at the SMTP address level. We propose building deep learning models at the message level. We train four individual CNN models: (1) a content model with subject and content as input, (2) a sender model with sender email address and name as input, (3) an action model by analyzing email recipients’ action patterns and generating target labels based on senders’ opening/deleting behaviors and (4) a salutation model by utilizing senders’ "explicit salutation" signal as positive labels. Next, we train a final full model after exploring different combinations of the above four models. Experimental results on editorial data show that our full model improves the adjusted-recall from 70.5% to 78.8% and the precision from 94.7% to 96.0% compared to the old production model. Also, our full model significantly outperforms a state-of-the-art BERT model at this task. Our new model has been deployed to the current production system (Yahoo Mail 6).