Wow, the MTA actually listens to their riders:
Dear NYC Transit E-mail subscriber:
Thank you for your participation in the e-mail pilot and providing us with your comments and suggestions.
In response to customer requests, starting this week we will send you one e-mail with scheduled service changes only for the lines you requested.
This streamlined e-mail will be sent to you on Fridays instead of Wednesdays, beginning July 1. The July 1 advisories will contain the information for this weekend and the following weekend (July 9-10).
In the coming months, we will be expanding the program to offer e-mail for all service changes: weekday, late at night, and special alerts for unexpected service disruptions.
We appreciate your patience and your valuable feedback. Please let us know how this new change is working for you. You are helping us build and improve this program.