If your Mac is connected to the Internet but suddenly starts asking for your password, you should generally try again later, and if necessary work with your email provider to resolve. If you're using Apple's iCloud Mail, learn how to resolve issues with iCloud Mail.

Why is Mail asking for your password?

Either way, the password popup prompt is probably going to be ironed out in a future update to Mac OS X to stop confusing users, as it may just be a bug. If you have any other resolutions, particular experiences, comments, or thoughts on seemingly random iCloud password dialog prompts in MacOS and Mac OS X, share them in the comments.

In the right pane, you’ll see two policies labeled “Require a Password when the computer wakes (plugged in)” and “Require a Password when the computer wakes (on battery)“. Double-click on them to modify and set the policies to Disabled. Reboot your computer for the policies to take effect. OSX did an update last night (I'm on 10.11.3) and after it reboot it asked me for the 'Setup User' password, see photo below. I am aware that you can just reboot to get around this issue - but as we have seen it multiple times in our office now, we'd like to know exactly why it is happening.

Mail asks for your password when it is connecting to your email provider, but can't connect to your email account because your email provider isn't accepting your email password.

Your email provider may reject your password for several reasons, including:

• You're not using your current email password. If you updated the password on another device, make sure that you're using the same password on your Mac.
• Your email provider needs you to update or reset your password for security reasons. For example, if you're using Google’s two-step verification, your Gmail account in Mail requires the appropriate app-specific password.
• Your email provider deactivated or suspended your account. Contact your email provider for help.
  

Check your password in Internet Accounts preferences

Depending on the type of email account you're using, you might be able to correct the password as follows:

1. Quit Mail. If it doesn't quit, you can force it to quit.
2. Choose Apple menu  > System Preferences, then click Internet Accounts.
3. Select your mail account in the sidebar.
4. If you see a password field for your account, delete the password and type the correct password.
   
5. Close System Preferences, then open Mail and try using your account again.

If Mail still asks for your password, the password is probably incorrect. Your email provider can help you verify your email settings and make sure that you're using the correct password.

Test using webmail

Os X Restarts Asking For Setup User Password Free

Many email providers offer webmail, which is a way to use email with a web browser such as Safari, instead of with an email app such as Mail. For example, if you're using an iCloud Mail account, you can use iCloud.com to send and receive email.

Because the password that you use with Mail is usually the same password that you use with webmail, try signing in to webmail with that password. If it doesn't work there either, your password is probably incorrect. Your email provider can help you verify your email settings and make sure that you're using the correct password for the Mail app.

Remove your account, then add it back

If no other solutions work, try setting up your email account again. To do that, first remove your email account, then add the account back.

Learn more

Os X Restarts Asking For Setup User Password Download

• If you're using Apple's iCloud Mail, learn how to resolve issues with iCloud Mail. The password that you use with iCloud Mail is your Apple ID password. Learn what to do if you forgot your Apple ID password or want to change your Apple ID password.
• If you forgot or want to change the email password for a different email service, contact the email provider or request a password reset from their website.