Feature · Extend Inbox
Extend Your Temporary Inbox Without Starting Over
Learn how MailOnce Extend Inbox works, when the option becomes available, and how a free temporary inbox can remain active for up to 3 hours.
8 min read
Quick answer
A MailOnce inbox starts with 1 hour. When 15 minutes or less remain, Extend Inbox can reset the remaining time to 1 hour. It does not add an extra hour on top of the time already left, and a free inbox can stay active for no more than 3 hours in total.
Why extend a temporary inbox?
Sometimes a verification flow takes longer than expected. You may be waiting for a delayed message, finishing a signup, testing a service, or simply need the same address a little longer.
Extend Inbox is designed for that short continuation. It keeps the current temporary address and inbox alive instead of forcing you to change addresses in the middle of the task.
When does Extend Inbox become available?
The option is intentionally time-sensitive. It becomes useful near the end of the current session, when 15 minutes or less remain.
This keeps extension tied to a real need rather than turning a temporary inbox into an indefinitely renewable mailbox.
What happens when you press Extend Inbox?
Extending does not add 60 minutes to whatever time is already on the clock. It resets the remaining time to 1 hour.
For example, if 10 minutes remain and you extend, the timer returns to 60 minutes—not 70. Your address and current inbox continue while that renewed window is active.
The timer rule
15 minutes or less remaining → Extend becomes relevant → remaining time resets to 1 hour → total free inbox lifetime never exceeds 3 hours.
Why MailOnce resets the timer instead of stacking hours
Stacking time early would let unused minutes accumulate and would make the temporary lifetime much harder to reason about. A reset is simpler: when the extension window is available, you can restore one usable hour.
That design gives legitimate short tasks more breathing room while keeping a clear boundary against abuse and long-term storage.
How the 3-hour free limit works
A free MailOnce inbox can remain active for a maximum total lifetime of 3 hours. Extensions help you reach that ceiling when needed; they do not move the ceiling.
Once the free lifetime limit has been reached, the inbox cannot be extended indefinitely. MailOnce remains a temporary-email service rather than a permanent mailbox.
What happens after the inbox finally expires?
When the active lifetime ends, the inbox is no longer available for normal use. MailOnce's retention and wipe policy is separate from the visible inbox lifetime: temporary data is retained only for the limited cleanup period defined by the service and then removed.
Do not treat an expiring inbox as a place to keep information you may need later.
When should you use a longer-lived mailbox instead?
Use Extend Inbox when a short task genuinely needs more time. If an account depends on future password recovery, receipts, ownership verification, support conversations, or long-term access, use a permanent email address you control.
The extension feature solves a timing problem; it does not change the temporary purpose of the inbox.
The practical takeaway
Extend Inbox is for finishing a short-lived task without losing the address you are already using. Think reset, not addition: the remaining timer returns to one hour, while the total free lifetime stays capped at three hours.
Need a little more time with the same inbox?
Create a MailOnce temporary address and extend it near expiry when your task is not finished yet.
Create temporary email →