I received a similar letter from UA yesterday. My offer acknowledged I flew a full fare C trip to Asia last summer and offered me double miles (on top of my 1K double miles bonus) for the second of two full fare trips in full Y, C, or F to Asia taken prior to September 15.
I'm flying C (and bumping up to F) next week--but the second won't come for a couple of months. Basically it's an offer for 16,700 miles. Nice, but isn't going to help me.
At least they are offering some of the targeted mailings to 1Ks.