Will this email bounce? Check before you hit send
To find out if an email will bounce before you send it, enter the address here. The tool checks the syntax and domain, then asks the domain's mail server whether the mailbox exists and disconnects before sending. You get yes, likely, unlikely or can't tell. Providers that hide mailbox status always come back can't tell, never safe.
Sample result
Yes, mail to jane.old@acme.example will bounce: the mail server says the mailbox doesn't exist.
- jane.old@acme.example
- Mail server said
- Mailbox not found
- What to do
- Remove it from your list
What this means for you
Remove it before you send; a hard bounce counts against your domain.
- Asks the mail server about the mailbox
- Catch-all and hidden providers say can't tell
- The reason and what to do with every answer
- Five checks a minute, no account
- Bounce
- Single address
- No signup
By SimpleVerifier Team · Last updated
How do I check if an email will bounce?
- Type or paste one address, such as
jane@acme.com. - Press Will it bounce? The tool checks the format, the domain's mail server and disposable domains, then asks the mail server about the mailbox at the
RCPT TOstep and disconnects before any message is sent. - Read the answer: Yes (it will bounce), Likely (a throwaway inbox), Unlikely (the server confirmed the mailbox) or Can't tell (the server wouldn't say).
- Follow the "What to do" line under the answer, then check the rest of your list the same way before a campaign.
Example
- You enter
- One address:
jane.old@acme.example, where the mail server rejects the mailbox. - You get
- Yes, it will bounce, with the reason "Mailbox not found" and the advice to remove it. An address at a catch-all domain comes back Can't tell ("Accepts all addresses"), and
name@outlook.comcomes back Can't tell because Microsoft's consumer domains aren't probed. A confirmed mailbox comes back Unlikely, never a guarantee. - Limits
- Five checks a minute per IP address, one address at a time, no account needed.
How can I tell if an email will bounce without sending it?
Ask the receiving mail server the same question a real delivery would, and stop before the message. A sending server connects to the domain's MX host, says who the mail is for with RCPT TO, and the server either accepts that recipient or rejects it. RFC 5321 defines the replies: a 550 at that step means the mailbox is unavailable, which is exactly the hard bounce you would have got.
This tool runs that conversation and disconnects before any message content is sent, so the address owner receives nothing. Before that it checks the things that bounce without asking anyone: an address that isn't validly formed, or a domain with no mail server at all. The hard vs soft bounce guide explains which failures are permanent.
What do yes, likely, unlikely and can't tell mean?
Yes: the address will bounce. The mail server said the mailbox doesn't exist (usually 550 5.1.1), the domain has no mail server, or the address is malformed. Likely: the address is at a disposable inbox service; it may accept mail today, but these inboxes are deleted quickly and nobody reads them. Unlikely: the server confirmed the mailbox and refused a made-up address at the same domain, so its yes means something.
Can't tell is the honest answer whenever the server's reply proves nothing: a catch-all domain that accepts every address, a provider that won't reveal mailboxes, a role address like info@ that isn't probed, or a server that deferred or didn't answer. It is never shown as safe to send, because these are the addresses that bounce after a campaign goes out.
Why can't you tell for Outlook, Hotmail or iCloud addresses?
Because those providers don't tell anyone. Microsoft's consumer domains (outlook.com, hotmail.com, live.com) and Apple's (icloud.com, me.com) don't give outside servers a reliable answer about whether a mailbox exists. Rather than guess, the verifier skips the mailbox probe for them and the answer is can't tell.
Yahoo and AOL often won't give a usable answer either. For those addresses the safest move is a small first send and a close watch on bounces. Provider-specific details are on the Outlook, Yahoo and iCloud checkers.
Should I check one address or the whole list?
One address answers one question: will this email to this person bounce? A campaign raises the list version: how many of these will bounce, and will that cross my platform's limit? Several sending platforms review accounts with bounce rates above a few percent; bounce rate limits by platform lists the published lines.
So check single addresses as they come in (a form, a business card, a reply), and run the whole list before each campaign. The bounce rate estimator gives a quick range from what's visible without asking any server; verifying the list gives each address the same answer this page gives one.
Who uses this tool, and for what?
- Sales reps
- Check a guessed or copied prospect address before the first email, so the sequence doesn't start with a bounce.
- Recruiters
- Confirm a candidate's address from an old CV or a profile before writing, and see when a provider won't say either way.
- Support and ops
- A customer says they never got the email: check whether the address on file would bounce, and spot the typo domain.
What can’t this tool tell you?
- Can't tell is common: catch-all domains, Outlook.com, Hotmail, iCloud and often Yahoo don't confirm mailboxes.
- Unlikely means the mailbox existed at the time of the check, not that anyone reads it.
- One address at a time, five a minute. Lists need the bulk verifier.
- Free checks share a daily mailbox-check allowance; when it runs out the answer is can't tell until 00:00 UTC.
Common questions
- How do I know if an email address will bounce?
- Ask its mail server. Enter the address above: the tool checks the format and domain, then asks the server at the RCPT TO step whether the mailbox exists, and disconnects before sending. A rejection means the email would hard bounce.
- Does checking an address send an email to it?
- No. The check ends after the mail server answers about the recipient, before any message is transmitted, so nothing arrives in the inbox and the owner isn't notified.
- Why does it say can't tell instead of safe?
- Because the server's answer proved nothing: it accepts every address (catch-all), it hides mailbox status (Outlook.com, Hotmail, iCloud), the address is a role inbox that isn't probed, or the server didn't answer clearly. Those addresses can still bounce, so they aren't shown as safe.
- If it says unlikely, can the email still bounce?
- Yes, occasionally. Unlikely means the mailbox existed when checked. A full mailbox gives a soft bounce, and a mailbox closed after the check gives a hard bounce. Re-check addresses that are more than a few months old.
- What happens if I send to an address that bounces?
- You get a bounce message back, and the hard bounce counts against your domain with mailbox providers and your sending platform. A few are normal; a high bounce rate can get campaigns paused or accounts reviewed.
- Is the bounce check free?
- Yes, five checks a minute with no account. To check a whole list, sign in with Google for 100 free email checks, no card, or use a paid plan.
Sources
That was one address. Most people have a list.
The free checker does five addresses a minute, one at a time — fine for spot-checking, useless for a CSV of 40,000.
- Upload a CSV up to 100,000 rows
- Valid, risky and invalid exported as separate files
- Repeat checks free for 14 days, no new connections
One plan, cancel anytime, no contract. Sign in with Google and your first 100 email checks are free, no card. The free tools stay free either way.