This is not a genuine AT&T email or link!

If you have clicked this link believing it to be a legitimate link from AT&T or any other company, you have been tricked. This link was actually pointing to a malicious phishing / malware page until it was changed to this message on 07 February 2019. Had you gone to the original page, you would have now been prompted to download an infected Word document containing a trojan virus downloader.

How can you avoid this happening in future?

Reconsider your approach towards clicking links in emails, and take a "zero-trust" approach - even if something appears to be from a company of which you are a customer, always verify before opening.

NEVER open an attachment or click on a link in an email, unless you have requested a link or a file from someone you know.

Consider using an email client which highlights potentially fake / impersonated emails and integrates with antivirus.

Even if you have the smallest amount of doubt, contact the company shown as the sender and verify if they have sent you an email recently - particularly if it's asking for personal details, or suggesting you click to check a bill or account details.

You should also immediately virus scan your computer immediately using a good product as you may already be infected by other similar malware attacks - Avira, Avast, Kaspersky, Bitdefender or F-Secure are good choices. Windows Defender is NOT good enough on its own. Also invest in a good firewall product, the antivirus vendors listed above all offer products for reasonable prices.