The next time you sign up for a coupon code or retail promotion, use these apps to avoid spam text and email messages. WHEREVER WE GO on the web, we're asked to sign up for new accounts—for streaming platforms, app trials, delivery services, and so on—and that puts a strain on the email accounts and cell numbers we use every day. Even when these services you sign up for are legit, you don't necessarily want a deluge of promotional offers, feature updates, and other miscellany filling up your inbox. Then there are the services that you'd rather just try out first, before you start sharing anything personal like an email address or phone number. For all these reasons, a disposable email address or phone number (or both) can be very handy. If a particular service starts spamming or robocalling you, you can just close down the temporary contact and walk away. When it comes to email addresses, you've got a number of free or freemium options to pick from—e...