Clock starts on generation
Open the homepage, receive an address, and the countdown begins at 3:00:00, ticking every second on screen.
Limits & rules
How long can you keep a disposable email? Limits at a glance
Whether you treat it as a burner email for a quick signup or an anonymous inbox for a forum, know the boundaries first: how long the address survives, what happens to attachments, how big a message can be, and how many aliases you may create. Every hard rule OnceEmail enforces is on this page — no fine print elsewhere.
First visit? Skim the quick how-to guide, then come back here to double-check the numbers.
30-second answers
- 3 hoursDefault lifetime for a disposable address — extend anytime
- 24 hoursMaximum age for one address, then rotate
- 100MBWhole-message size cap; larger mail is rejected
- 100Forwarding aliases allowed per account
- 30 daysOnline archive for relay mail
Time limits: 3 hours by default, 24 at the ceiling
Unlike classic ten-minute mail, a OnceEmail temporary address starts with a 3-hour window — enough for signup, verification, and a download link.
Refill with one tap
Each Extend 3 hours click resets remaining time to a full 3-hour block. Tap as often as you like until you hit the cap.
No more extensions
From the moment the address was born, 24 hours is the absolute maximum. After that, the page prompts you to request a new one.
Address and mail deleted together
Nothing is archived and nothing can be restored — there is no “view old messages” feature for disposable inboxes.
Heads-up: refresh the tab, close the browser, or open the link on another device within 3 hours and the same inbox comes back — destruction follows the timer, not your presence online. Step-by-step recovery is in the how-to guide.
Attachments and size: one standard, two products
Disposable inboxes and forwarding aliases treat attachments very differently. Every tier is measured on the whole message — body plus files combined.
Disposable email: body only, no stored files
After delivery, attachment bytes are not kept. A paperclip in the list only means the original sender included a file — there is no viewer and no download inside the temporary inbox.
Messages over 100MB are rejected at the server; they never appear in your list.
Expecting contracts or photos? Switch to a permanent forwarding alias instead.
Forward and keep attachments
Full delivery to your real inbox, files preserved in the 30-day web archive for online viewing or download.
Forward, do not archive files
The complete message including attachments reaches your real mailbox, but the web copy keeps body text only — the detail view notes that files were forwarded.
Rejected outright
No forward, no archive. For payloads this large, ask the sender for a cloud link instead.
Forwarding aliases: quota and naming
Each account may hold up to 100 aliases. The finished address is your prefix + @onceemail.com. Follow the rules below and creation succeeds on the first try.
Prefixes that pass validation
- Starts with a letter
- 3–30 characters long
- Letters, digits, dots (.), hyphens (-), underscores (_) only
- Stuck? Tap Random for a natural-looking prefix, or leave blank for auto-assign
Requests that get rejected
- Reserved system names such as admin or support
- Prefix already taken by another user
- Starts with a digit or symbol, or shorter than 3 characters
- Creating when all 100 slots are full — delete unused aliases to free one
Four archive statuses
- Forwarded
Delivered to your real inbox and mirrored in the 30-day web archive.
- Blocked
Flagged as spam and not forwarded; appeal from the detail view if it was a mistake.
- Failed
Delivery hit an error — retry manually from the detail page with live feedback.
- Pending
Just arrived and queued for forwarding; status updates on its own shortly.
Complete rules reference
Everything above and a few details we did not spell out elsewhere — this table is the full boundary of the service.
Swipe to see all columns
| Item | Rule | Notes |
|---|---|---|
| Disposable email | ||
| Default lifetime | 3 hours | Extend anytime before the cap; each extend refills to 3 hours |
| Maximum age | 24 hours | Counted from creation; rotate to a new address afterward |
| Attachments | Not stored | Paperclip icon only; no online view or download |
| Size limit | 100MB whole message | Body plus attachments combined; over limit rejected |
| Recovery | URL param + local storage | Same inbox on refresh or another device while not expired |
| Sending | Receive only | Addresses cannot be used to send or reply — anti-abuse by design |
| Forwarding aliases | ||
| Quota | 100 per account | Delete old aliases to reclaim slots |
| Prefix format | Letter first, 3–30 chars | Letters, digits, dot, hyphen, underscore |
| Reserved names | Not available | admin, support, and other system holds |
| Attachment tiers | 50MB / 100MB lines | ≤50MB forward + archive; 50–100MB forward only; >100MB reject |
| Web archive | 30 days | Auto-purged afterward; mail already in your real inbox stays |
| While paused | Incoming mail dropped | Not forwarded, not archived — nothing replays when you resume |
| Login & security | ||
| Sign-in | Email code, no password | 6-digit verification; new emails auto-register |
| Code resend | 60-second cooldown | Rapid repeats are temporarily blocked |
| Session length | 7 days | Expires quietly; verify again to continue |
| Two-factor auth | Optional TOTP | 6-digit codes from an authenticator app |
| Pricing | ||
| All features | Free | No paid tier, no usage caps, no hidden fees |
Three boundaries worth remembering
Most people never hit them — knowing upfront saves surprises later.
Expiry is permanent
When a disposable address dies, the inbox is gone. Register banks, employers, and government portals with your real email or a forwarding alias — not a burner.
Paused aliases drop mail
While paused, messages are neither forwarded nor archived. Nothing is queued for later — confirm nothing critical is in flight before you pause.
Receive-only — no replies
Neither disposable addresses nor aliases can send mail. That is intentional abuse prevention. When someone needs a reply, use your real inbox.
Rules clear? Put them to work
That is the entire playbook — nothing hidden in footnotes. Grab a disposable address to test, or sign into the relay console and create your first alias.