I really don't get why everyone assumes it's a real email. Please google myusairways.com
myusairways is owned by us airways as you can see their registration below, when people spam they are trying to get info from you this email is just letting you know information with the option to cancel you reservation.
Registrant:
US Airways
US Airways
4000 E. Sky Harbor Blvd RWE-PPA / McFarlane
Phoenix, AZ 85034
US
Email: Email Masking Image@usairways.com
Registrar Name....: CORPORATE DOMAINS, INC.
Registrar Whois...: whois.corporatedomains.com
Registrar Homepage:
www.cscprotectsbrands.com Domain Name: myusairways.com
Created on..............: Thu, May 08, 2003
Expires on..............: Thu, May 08, 2014
Record last updated on..: Sun, May 05, 2013