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When OrbiSearch marks an email address as Safe, it means a conclusive or high-confidence signal was found that the mailbox exists and is accepting mail. This is the strongest verification result possible without actually sending an email. Understanding what that guarantee covers — and where it ends — helps you set accurate expectations and handle edge cases in your workflow.

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What “Safe” actually means

A Safe result tells you that at the time of verification, OrbiSearch determined the mailbox exists and can receive mail. The deliverable substatus is assigned when this confirmation is made with high confidence through standard mail server handshake protocols and proprietary probes.
Verification works by communicating with the recipient’s mail server and checking whether it accepts the address. OrbiSearch does not send any actual email to do this.

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Why a verified-safe email can still bounce

All email validation tools verify whether a mailbox exists. But a mailbox existing is not the same as your email being delivered to it. After a mail server accepts an incoming message, additional layers of filtering and policy can reject or discard it. Common causes include: Allowlist or sender policy restrictions Some organisations configure their mail servers to only accept email from pre-approved sender domains. If your domain is not on their allowlist, your message will be rejected even though the mailbox is real and active. Content or reputation filtering Corporate email gateways may reject messages after acceptance based on content analysis, sender reputation scores, or anti-spam policies. These checks happen after the mail server has already confirmed the address exists — after the point at which any validation tool can see. Mailbox changes after verification A mailbox that existed at the time of validation may be disabled, migrated, or deleted before you send your campaign. OrbiSearch results are cached for 24 hours, but if significant time passes between verification and sending, the state of the mailbox may have changed.
The longer the gap between verification and sending, the higher the chance that mailbox state has changed. Re-verify lists that are more than a few days old before sending.

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What OrbiSearch cannot detect

Some delivery failures are outside the scope of what any email validation tool can detect:
  • Sender allowlists: Whether a receiving domain will accept mail specifically from your sending domain or IP.
  • Content-based filtering: Whether the content of your message will trigger spam or policy filters at the destination gateway.
  • Post-verification changes: Any change to a mailbox that occurs after the verification was performed.
  • Internal routing rules: Forwarding rules, auto-responders, or internal policies that affect what happens to a message after it is accepted.
The policy_blocked substatus (which returns a Risky status) indicates that the recipient’s mail gateway blocked OrbiSearch’s verification attempt. The address may still be deliverable — it just could not be confirmed. See Email Verification Statuses Explained for a full substatus reference.

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Can any tool guarantee 100% deliverability?

No. No email validation tool can guarantee that a verified address will successfully receive your message. Validation tools operate at the level of mailbox existence — they confirm whether an address is real. Deliverability depends on factors that occur after that confirmation, including your sending infrastructure, your sender reputation, and the recipient domain’s filtering policies. OrbiSearch has market-leading accuracy, but post-acceptance filtering is outside the scope of what any validation tool can detect.
If you are experiencing high bounce rates despite verifying with OrbiSearch, the likely causes are sender reputation issues, content filtering, or a stale list. Deliverability tools and inbox placement tests can help diagnose these problems — they complement verification rather than overlap with it.

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What to do if a Safe email bounces

Occasional bounces on Safe-verified addresses are normal. If you see a bounce on an address OrbiSearch marked Safe:
  1. Check the bounce reason. Your email service provider’s bounce report will include a bounce code and reason. A 550 5.1.1 (mailbox not found) on a recently verified address is worth investigating; a 550 5.7.1 (policy rejection) is a sender-side or content filtering issue unrelated to verification accuracy.
  2. Check when the address was last verified. If the verification is more than a few days old, the mailbox may have changed state since then. Re-verify the address to get a current result.
  3. Contact support if you suspect a genuine error. If a recently verified address bounces with a mailbox-not-found code and re-verification returns the same Safe result, contact OrbiSearch support with the address, the verification timestamp, and the bounce details. Persistent discrepancies help improve accuracy for all users.