A Walmart phishing campaign is underway that attempts to steal your personal information and verifies your email for further phishing attacks. The collected information is used to conduct identity theft attacks, gain access to your other accounts, or perform targeted spear-phishing attacks. If you click on the ‘Update Address’ button, the phishing email will cause your mail program to create a new email with the subject ‘Update my Address!’ that will be sent to multiple email addresses under the attacker’s control.
Source: https://www.bleepingcomputer.com/news/security/beware-walmart-phishing-attack-says-your-package-was-not-delivered/