Yahoo users who have received email messages like the one below, which claim that unusual activity has been detected on their accounts and should call 855-203-6080, should delete the email messages and not follow the instructions in them. This is because the email messages are phishing scams sent by cyber criminals and NOT by Yahoo, to trick Yahoo users into clicking on the link in the fake and malicious email message that goes to a phishing website that steals Yahoo email account username and password.
The "Unusual Activity With Your Yahoo Account" Phishing Scam
From: "EMAIL SECURITY" <01718039.DCC9B9557CD39E4F7449D1agtdddhkkui@shleevqaxge.com>
Date: November 15, 2017 at 12:36:56 PM EST
Subject: Account Cancelation
We Have Detected Unusual Activity With Your Yahoo Account
Login Has Occurred On 11/10/2017 @ 9:38 AM
From IP: 34.26.95.326 Geo: Eastern Russia
If This Was Not You Please Call the Email Security Department
855-203-6080
Yahoo users who have already received the phishing email messages, and who have followed the instructions in them, are asked to change their Yahoo account passwords immediately before their accounts are hijacked by cybercriminals and used fraudulently.