I am not sure what "close his email box" means. If you don't use Thunderbird yourself you could remove it. I can't be sure that the usual uninstall procedure works with Thunderbird, though I'd ask you to try this first. Otherwise you can just go the Thunderbird folder and remove it in your file manager. If you do want to carry on using Thunderbird yourself, you can remove your husband's account so it doesn't show in Thunderbird. Select his account, right-click it, select "Settings". When the Account Settings panel shows, ensure the unwanted account is still selected, then at the bottom, click on '''Account Actions''' and then '''Remove Account'''. Note that you won't be able to remove the default account, so you may first have to set another account as the default. You might also consider approaching your email provider to ask about closing this account permanently, though no doubt you will have all the usual difficulties that arise in managing the affairs of a deceased person. My commiserations on your loss.