Planning Alerts a web-based service that sends you e-mails to alert you of any planning applications granted near to where you live, have recently been threatened with legal action by Royal Mail unless they pay a £4000 yearly fee to access the postcode database.

There are several forms of action that can be taken towards this:

Write to your MP:

Tom Watson MP has tabled an Early Day Motion in Parliament calling on
the Royal Mail to allow non-profit organisations to use the postcode
database for free. Please write to your MP asking them to sign this
Early Day Motion (number EDM 2000) and protest at the actions of The
Royal Mail.

You can write to your MP here

Sign the petition:

There is a petition up on the Number 10 website regarding this situation:

Sign the petition here