I actually thought it was an interesting mail received yesterday. I did not know for example I could register gift cards for the program.

When in doubt of anything like this, go directly to the website without clicking on the e-mail. Not necessary in this case as it was a legitimate mail and all the links went where they should have gone, but in the future get out of the habit of clicking links in mails and type in the website address if you have any concern.

If you did not register for mp dining and have a Mileage Plus visa or debit card I believe you would have been automatically registered, that may be why some people get it who did not know they were part of the program.