Email Verifier
WarmySender includes a built-in Email Verifier to validate email addresses before campaigns — reducing bounces and protecting sender reputation. Included free with all paid subscription plans.
Plan Limits:
- Pro ($14.99/mo): 300 verifications/month
- Enterprise ($69.99/mo): 1,500 verifications/month
- Free trial, Starter, and Lifetime plans: Not available (upgrade to Pro+)
- Each plan also has a daily allowance equal to its monthly total ÷ 30 (about 10/day on Pro, 50/day on Enterprise); a verification needs room in both the monthly and the daily allowance
- Monthly usage resets on the 1st of each month (UTC); the daily allowance refreshes each day
- Unknown results are free — they never count against either allowance
- Your plan's number is a FREE ALLOWANCE, not a ceiling: one-time verification credit packs verify beyond it. Purchased credits never expire, skip the daily pace, and are used automatically only once your free allowance is spent — so you can always clear a big list today without changing plans
How It Works:
The verifier asks the receiving mail server whether an address can accept mail — without ever sending an email to it. Nobody is contacted, nothing arrives in anyone's inbox, and the check never runs through your own connected mailboxes, so your sender reputation is never put at risk to test a list.
What each check establishes:
1. Whether the address is written in a usable form
2. Whether the company can receive mail at all
3. Whether that specific mailbox exists and accepts mail
4. Whether the company accepts every address (a catch-all — see below), which means no tool can confirm one specific inbox there
5. Whether we already have first-hand proof: if your own mail has reached that inbox before, that real delivery is stronger evidence than any live check, and we use it instead. Results confirmed this way are marked 'Real delivery' in your results.
Most addresses come back in a second or two. Larger lists are paced deliberately rather than checked all at once — that pacing is part of what keeps the answers accurate.
Important: verification tells you an address is good AT THE MOMENT IT WAS CHECKED. It is not a permanent guarantee — people leave companies and mailboxes get closed. See 'Why a verified list can still bounce' below.
Accessing the Email Verifier:
Navigate to Email > Email Verifier in the sidebar (look for the green 'New' badge). You'll see three tabs:
--- Tab 1: Batch Verification (CSV Upload) ---
Verify a list of email addresses from a CSV file.
How to use:
1. Click 'Upload CSV' and select your file
2. The system automatically detects the email column (supported headers: email, email_address, e-mail, contact_email, emailaddress)
3. If no header matches, the system checks each column for email-formatted values
4. Emails are deduplicated, validated, and sanitized before processing
5. Verification processes gradually in the background (not all at once) to ensure accuracy and avoid rate limits
6. Monitor progress with the real-time progress bar — the page auto-refreshes every 3 seconds
7. View results filtered by status (All, Valid, Invalid, Risky, Unknown)
8. Download the complete results as a CSV when finished
CSV Requirements:
- File must contain an 'email' column (or similar header name)
- Maximum 20,000 emails per file — split a larger list into several files and upload them one at a time; every one lands in the same place
- Maximum 10MB file size
- Supports: quoted fields with commas (RFC 4180), UTF-8 with BOM (Excel exports), Windows/Mac/Unix line endings
- Duplicate emails within the file are automatically removed
--- Tab 2: Verify a List ---
Verify emails directly from your existing prospect lists — no CSV export/import needed.
How to use:
1. Select a prospect list from the dropdown
2. Click 'Verify List'
3. The system extracts all email addresses from the list's prospects (skips prospects without emails and LinkedIn-only placeholders)
4. Verification runs in the background with real-time progress
5. When complete, two things happen automatically:
a) A NEW list called '[Your List Name] - Verified' is created containing only prospects with valid or risky emails
b) Prospects with invalid emails are automatically marked 'invalid' across your contact database, so every campaign skips them from then on
6. The verified list appears in your Prospects page ready to use in campaigns
This is the recommended workflow before launching any campaign:
1. Import your prospects into a list
2. Go to Email Verifier > Verify a List
3. Select the list and verify
4. Use the auto-created '[Name] - Verified' list in your campaign
--- Tab 3: Single Check ---
Verify a single email address instantly.
How to use:
1. Enter an email address in the input field
2. Click 'Verify' or press Enter
3. See instant results: status, MX host, catch-all detection, and response time
4. Rate limited to 20 verifications per minute per workspace
Verification Statuses:
- Valid — The email address exists and can receive mail. Safe to send. Shown with a green badge.
- Invalid — The email address does not exist, the mailbox is full, the domain has no mail server, or it's a known disposable email. Do not send. Shown with a red badge.
- Risky — The domain is a 'catch-all' that accepts all addresses (e.g., small companies using Google Workspace catch-all). The email probably works but cannot be confirmed. Send with caution. Shown with a yellow badge.
- Unknown — The mail server temporarily refused the check (greylisting, rate limiting, or server timeout). Not invalid — try again later. Shown with a gray badge.
Catch-All Domains Explained:
Some domains are configured to accept emails sent to any address (e.g., [email protected] works). When the verifier detects this, it marks the email as 'risky' because it cannot confirm the specific mailbox exists. About 15-20% of B2B domains are catch-all. These emails are usually deliverable, but bounces are possible.
Batch Management:
- All your verification batches are listed in the left panel with status indicators
- Click any batch to see detailed results on the right
- Filter results by status using the filter buttons
- Download completed batches as CSV (available for 1 day after completion)
- Cancel in-progress batches — pending verifications are stopped immediately
- Your monthly usage is shown in the page header ('X / Y used this month')
Monthly Usage:
- Displayed in the header as a badge: 'X / Y used this month'
- Counts all emails submitted for verification (CSV uploads + list verifications)
- Resets on the 1st of each month (UTC)
- If you use up the free allowance, you'll see a clear message showing your usage — add verification credits to carry straight on (they never expire and skip the daily pace), or wait for the allowance to refresh
- Single email checks are rate-limited separately (20/min) but do not count against the monthly limit
Prospect Limits by Plan:
Each plan has a maximum number of prospects you can store:
• Pro: 10,000 prospects
• Enterprise: 100,000 prospects
• Ultimate: 300,000 prospects
• Existing prospects are never deleted on plan changes — you just cannot add new ones if you're over the limit
Data Retention:
- Verification results CSV files are stored for 1 day, then automatically deleted
- Batch records and individual results remain in the database indefinitely for your reference
- Verified prospect lists (created from 'Verify a List') are permanent and behave like any other prospect list
Best Practices:
- Always verify email lists before launching a campaign — this is the single most effective way to prevent high bounce rates
- Use 'Verify a List' instead of CSV upload when your contacts are already in WarmySender — it's faster and automatically creates a clean list
- Remove or exclude invalid addresses before sending — the 'Verify a List' feature does this automatically
- Re-verify lists that are more than 30 days old, as email addresses can become invalid over time
- Use the verifier after importing from external sources (purchased lists, scraped data, etc.)
- Combine with Bounce Shield for maximum deliverability protection
- For catch-all domains (marked as 'risky'), the email likely exists but cannot be confirmed — include them in campaigns but monitor bounce rates
- Start with a small test batch if you're verifying a large purchased list — check the valid rate before committing your full monthly quota
FAQ:
Q: Does the verifier send any emails?
A: No. It asks the receiving mail server whether the address can accept mail and stops there — no message is ever delivered, and the person is never contacted.
Q: Will verification affect my sender reputation?
A: No. Checks run on our own separate infrastructure, never through your connected mailboxes, so nothing you verify touches your sending reputation.
Q: Why are some results 'Unknown'?
A: Some mail servers temporarily refuse verification attempts (greylisting, rate limiting). This does not mean the email is invalid. Try again later or include them in your campaign with caution.
Q: What happens to invalid prospects when I use 'Verify a List'?
A: They are automatically marked with status 'invalid' in your prospect database. They remain in the original list but will be skipped by campaigns that filter by status.
Q: Can I re-verify the same list?
A: Yes. Each verification creates a new batch and a new verified list. This is useful for re-checking lists after 30+ days.
Q: Do single email checks count toward my monthly limit?
A: No. Single checks have a separate rate limit (20/minute) but do not deduct from your monthly verification quota.