My contacts are receiving spam from me that I didn't send

While no one else can sign up for the same email address that you use, there are ways people can gain access to your account or send emails that look like they're coming from you. Be aware of how this happens and the steps you can take to stop it.

Someone accessed your account

If your Yahoo account is compromised, someone has either learned your password or has hacked into your account to send messages from your email address.

Find out if this is the case and learn to secure the account.

Someone created fake emails from you

Someone has the email addresses of your contacts and is spoofing messages that look like they're coming from you. They may have current or previous access to your account or have compiled the addresses from an email you've sent in the past.

Have your contacts manually block the sender's true address.