13-04-2018 02:19 PM - edited 13-04-2018 02:20 PM
Usually there's an option in your Internet browser.
For example in Firefox: Tools > Options > Privacy & Security > Permissions - Block Pop-up Windows.
But see the Exceptions button. Click that then add websites that have pop-ups that are essential to use. Webmail has some pop-up windows as does MyAccount. So you wouldn't want to miss those or you might think they're not working.