Goldpoints Plus is offering free Silver status and fast track to Gold.
The offer was sent to customers of Orange.
Based on that and the phone number given as an option for how to take advantage of the offer, I assume it’s intended for U.K. members.
To take advantage of this offer, contact the Member Service Centre at email@example.com or call +44 207 949 0379 and mention the promotional code indicated in your Orange mailing.
A promo code is required, and this Flyertalk thread gives it as SWSL06.