Two tools, two different promises
A temporary inbox and an email alias look similar from the signup form's side - both keep your real address out of the database. Behind the scenes they behave very differently. A temp mail address is a real, standalone inbox you use briefly and then burn, mail and all; 10 minute mail even destroys itself on a timer. An alias is a permanent forwarding rule: mail sent to the alias lands in your real inbox, relabeled.
The right choice depends on one question: do you want to receive this sender's mail, or merely survive their signup form?
When a temporary inbox wins
Temp mail is for transactions, not relationships. Downloading a whitepaper, grabbing a discount code, reading a paywalled article, testing your own signup flow - anything where you need to receive exactly one or two messages and never think about the sender again. The address does the job and then you burn it, which means it cannot leak later, cannot be sold later, and cannot be correlated with anything you do next month.
The other advantage is anonymity at creation. A Mail Vanish inbox requires no account and no personal details, so there is nothing linking the address to you even while it is alive.
When an alias wins
Aliases shine for relationships you intend to keep: shops you actually order from, services you log into monthly, newsletters you genuinely read. Because the alias forwards to your real inbox, you get the mail where you already live, and because each sender can have its own alias, you can identify who leaked or sold your address and shut off that one spigot without touching anything else.
The trade-off is that an alias is permanent infrastructure tied to your identity. The forwarding provider sees your mail flow, the alias itself becomes another identifier to manage, and deleting the alias does not un-deliver anything already forwarded into your real inbox.
The failure modes to avoid
Using temp mail for an account you will need to recover is the classic mistake - password resets go to an inbox that no longer exists. The reverse mistake is using a permanent alias for genuinely throwaway signups: now a marketing database holds a working, permanent route into your real inbox, which is exactly what you were trying to avoid, one hop removed.
The middle ground: a private address you own
Mail Vanish Private Emails sits between the two. Like an alias, the address is permanent and can forward - after explicit verification - to your real inbox. Like temp mail, it is a real standalone inbox with tracker blocking and sandboxed rendering built in, on premium domains that are not in the public disposable pools sites blocklist. Use free temp addresses for the transactions, and a private address for the handful of relationships worth keeping.