Troubleshooting bulk upload problems

Bulk verification mostly just works, but a handful of recurring failure modes show up enough to deserve a focused guide. This page is organized by symptom — find the description that matches what you are seeing, then read the explanation and fix.

"Invalid file format" on upload

We accept exactly two file formats: CSV (.csv) and TXT (.txt). Anything else — XLSX, XLS, ODS, PDF — gets rejected at upload time.

Common causes

• You exported as XLSX from Excel and uploaded that file. Re-export as CSV from the same file menu.
• You exported as "Numbers" from macOS Numbers. Use File → Export → CSV instead.
• Your file extension is right but the content does not match (e.g. an HTML file renamed to .csv). Open the file in a plain text editor to verify.
• Compressed file (.zip, .gz). We do not extract archives — decompress first, then upload the underlying CSV/TXT.

Fix

Open the file in your spreadsheet tool and re-export as CSV with UTF-8 encoding. If the file is genuinely a TXT export, make sure it is one email per line with no extra structure.

"File size exceeds 100 MB limit"

Hard limit on uploads is 100 MB per file. Files over that are rejected before any rows are read.

Fix

1. Split your file into chunks below 100 MB each.
2. Upload each chunk as a separate bulk job. They run independently.
3. Concatenate the results afterward in your spreadsheet tool.

"Maximum 1,000,000 emails per upload"

Even if your file is under 100 MB, the per-upload row limit is 1,000,000 emails. Lists above that need to be split.

"Insufficient credits"

The system checks credit balance before starting a job. If your balance is less than the number of unique emails in the upload (after duplicate removal), the job is rejected.

Fix

• Buy a credit top-up (PAYG) from the Buy Credits page.
• Enable auto-refill so balance drops auto-trigger top-ups.
• Split the file into smaller chunks if you only need to verify part of it now.

Upload stuck at 0%

The progress bar showing 0% for a long time usually means one of:

• Browser tab killed the upload. Some browsers terminate large uploads when the tab loses focus. Keep the tab active until the upload completes — once the file lands, the rest runs server-side and you can close the tab.
• Network interruption. A WiFi drop mid-upload aborts the request. Refresh and retry.
• Very large file on slow connection. A 90 MB file on a 5 Mbps uplink takes several minutes. Wait, or move to a faster connection.

Emails not detected in the file

The bulk pipeline auto-detects the email column by scanning the first few rows. Detection can fail when:

• The email column has a non-obvious header (primary-contact-email works, pe1 may not).
• Email values are wrapped in extra characters (<john@example.com>, "john@example.com").
• The file has merged cells, blank rows at the top, or other spreadsheet artifacts.
• Encoding is not UTF-8 (Latin-1 files with accented characters can break the parser).

Fix

1. Open the file in a plain text editor or spreadsheet.
2. Make sure the first non-blank row is the header.
3. Rename the email column to literally email for unambiguous detection.
4. Strip extra characters from email cells (<>, surrounding quotes, leading/trailing whitespace).
5. Save as CSV with UTF-8 encoding.

Job stuck in Processing for hours

Bulk verification time scales with list size and recipient-server response times. Expected ranges:

If your job is genuinely stuck (way longer than the typical range above with no progress), contact support@validemailchecker.com with the task ID — there is occasionally an upstream provider hiccup that needs manual restart.

"Completed with Warning"

This is not an error — it is the system signaling that the job finished but some addresses could not be reached by the verification engine (server timeouts, unreachable hosts, anti-spam blocks). For each unprocessed row:

• The address goes into a separate unprocessed file you can download from the Verification Details page.
• The credit is automatically refunded to your PAYG bucket.
• You can re-upload the unprocessed file later (often a few hours or a day) and many will verify successfully the second time.

No action required if the unprocessed count is small and you do not need those addresses right now. Re-upload if the count matters for your campaign.

Results look wrong (too many Invalids, too many Unknowns)

Way more `invalid` than expected

Usually a sign of:

• Stale list (addresses verified clean 6+ months ago and decayed since).
• Purchased or scraped list (lots of typos, fake signups, recycled traps).
• Form data without input validation (real users put junk in your form fields).
• Multi-line cells where addresses got merged or split incorrectly during upload.

Way more `unknown` than expected

Suggests:

• List heavily composed of corporate domains with aggressive anti-spam (verification timeouts).
• List from a country with restrictive mail-server policies.
• Upstream provider hiccup at the time of verification — re-running often clears these.

Credits for unknown results are auto-refunded, so the cost is zero. Re-upload the affected rows after 24 hours if you need definitive answers.

Cannot download results

Results are accessible from the Verification Details page (Uploads & Results → click View Results on any completed job). If you cannot download:

• Check the 15-day retention window — after the deadline, the job is auto-deleted and results are unrecoverable.
• Browser pop-up blockers can prevent the download. Allow popups for app.validemailchecker.com and retry.
• Very large exports (millions of rows) can take a moment to generate. Wait 30–60 seconds before assuming the export failed.

Still stuck?

Email support@validemailchecker.com with:

• The task ID of the affected job (visible on Uploads & Results).
• The exact symptom (what you did, what you expected, what happened).
• Browser + OS version if it is a UI issue.

We can re-run jobs, refund credits for genuine system errors, and diagnose anything the dashboard doesn't surface clearly.

Next steps