Should you block disposable email addresses?

If someone uses a temporary inbox to download your PDF, blocking it may simply mean they leave without the PDF. If they use it for an account they'll need to recover next month, there's a more practical problem.

Start with what you need the address for.

For account recovery, billing or important service notices, explain why the user needs an inbox they can keep accessing. Give them a way to change it. For a one-off download, you may not need an email address at all.

If you're trying to prevent repeated free trials, a disposable-domain block can be one filter. It won't stop someone creating more accounts with ordinary addresses. Measure the abuse you're trying to reduce, as well as legitimate signups lost to the block.

Be careful with privacy aliases. A forwarding address can remain in use for years. Services such as Apple's Hide My Email let people receive mail without sharing their main address. That is different from an inbox designed to disappear shortly after use.

A disposable flag is also fallible. Domain lists change, and an unfamiliar domain isn't automatically a temporary service. If you reject an address, explain the reason and offer a route for mistakes.

For a newsletter, confirmation tells you more than a blanket ban: can this person receive the message and complete the signup? After that, honour bounces and unsubscribe requests as you would for anyone else.