The Email I Received from att-mail.com
From: AT&T Online Services <firstname.lastname@example.org>
Date: Sat, Jul 6, 2019 at 8:31 AM
Subject: AT&T Profile update
Your online profile has been updated
Looks like you updated the contact email associated with your AT&T user ID
Online Security Questions & Answers Changed
We're serious about your security. So if you didn't make any changes to your account and think you got this message by mistake, call us at 877.285.1205.
Thanks for choosing us,
I'm not sure if the telephone number is legit or not because I cannot find it on AT&T's website. But, if you have doubts about an email message which appears to have been sent from AT&T, give them a call at 1.888.855.2338. The telephone number above was taken from AT&T's website at: https://tech360.att.com/att/contact-us/
Also, the att-mail.com domain, which the emails came from, is owned by AT&T, but it doesn't necessarily means the emails you were sent came from AT&T. Remember, email messages can be spoofed. Spoofed emails can be sent by cybercriminals from their email addresses and then be made to appear as if they came from AT&T email addresses when the recipients receive them.