退信郵件檢查器

它識別會退信的地址，讓您在傳送前先行移除。硬退信是永久性失敗（信箱不存在）。軟退信是暫時問題（信箱已滿）。我們同時偵測兩種類型，協助您從名單中移除高風險地址。

我們透過多個步驟檢查每封郵件：語法驗證、網域與 MX 記錄檢查，以及直接 SMTP 連線測試信箱送達性。整個流程在 3 秒內完成，準確率達 99.9%。

大多數使用者在清洗後退信率降低 85%。若您的名單退信率為 15%，驗證後預計可降至 2% 以下。效果立即可見。

可以。上傳 CSV 檔案，我們將為數千個地址進行退信風險評估。API 也支援表單和註冊的即時單一檢查。

快取結果在 200ms 內回傳，完整 SMTP 驗證平均需 1–3 秒。大量處理每小時可處理 50,000 個地址。

有。每個帳號每天可免費檢查 100 次，無需信用卡。升級前可測試所有功能，包含 API 存取。

A hard bounce is a permanent delivery failure — the email address doesn't exist, the domain is invalid, or the mail server rejected the message permanently. You should remove hard bounces from your list immediately. A soft bounce is a temporary failure — the mailbox is full, the server was unavailable, or the message was too large. Soft bounces may succeed on retry, but addresses that soft bounce repeatedly should also be removed. BillionVerify's email bounce checker detects both hard and soft bounce risks before you send.

To reduce bounce rate: (1) verify your list with an email bounce checker before every send to remove invalid addresses, (2) remove hard bounces immediately and monitor soft bounces, (3) use double opt-in for new subscribers, (4) avoid purchasing email lists, and (5) clean inactive subscribers every 6 months. Most senders see bounce rates drop by 85% after using BillionVerify's bounce detection before a campaign.

Email bounce detection works by running SMTP verification on each address before you send — testing syntax, domain existence, MX records, and whether the specific mailbox accepts incoming mail. This identifies hard bounce risks (non-existent mailboxes) and risky addresses (catch-all domains, role accounts, disposable emails) without sending a real email. The entire check completes in under 3 seconds per address.