I got the same email this morning, I also received a second email that states this:
"Dear XXXXX,
Thank you for choosing AT&T. Unfortunately, we need some additional information about your phone number transfer before we can complete your order. Please click on the following link to proceed with your number transfer:
https://www.wireless.att.com/lnp/
We apologize for the inconvenience and look forward to serving you. If we don't hear from you within 30 days, your order will be canceled.
AT&T"
I go to the site, put in my info and it says "in progress" I guess its because the port is pending until I activate the iPhone an that this is an automated message?