How to send E-mail and SMS notifications when one user outbid another user in drupal 7? I am new to auction idea of drupal 7. My client wants an checkbox to be implemented ,where users can select whether they require any e-mail notification /sms or both or none.I want to send e-mail and sms notification to the respective logged in user on the basis of bids placed by them!

I configured the mail and sms notifcation part .Can anyone let me  know how to send notifications when user checks the checkbox in drupal 7 on the basis of bid?
I would look at the Message module


  The Message module is the core of the message stack. It enables logging and displaying system events in a number of different use cases. Events that are recorded over time are sometimes call activity streams. Exportable messages subtypes can be created for different use cases with custom fields and display (view) modes.