Best Practices

Get the most out of email verification by knowing when to verify, how to act on results, and how to avoid common pitfalls.

When to verify

• Before a migration — clean your list before importing into a new ESP to start with a good sender reputation
• Before a bulk campaign — especially cold or re-engagement campaigns where bounce risk is high
• After 3+ months of inactivity — email addresses go stale faster than you think; employees leave, domains expire, inboxes fill up

Understanding your results

Each verified email is assigned a status. Here is what to do with each:

Segmentation strategy

• Important campaigns (product launches, transactional): export Safe only
• Regular sends (newsletters, updates): export Safe + Valid
• Re-engagement: consider including Risky with extra monitoring, but never include Invalid

Use the download filter in Step 3 (Results) of the wizard — select the segments you need rather than downloading everything and filtering manually.

Re-verification frequency

Email validity changes over time. People change jobs, domains lapse, and mailboxes get deactivated. For active sending lists, re-verify at least quarterly. High-volume senders with tight deliverability requirements may want to verify monthly.

Optimizing your credits

• Deduplication is automatic — the verifier removes duplicates before charging, so you are never billed twice for the same email in a single job
• Check the "What will happen" summary — before starting, Step 1 shows a summary box with the exact email count, duplicates removed, and credit cost so there are no surprises
• Extraction is free — paste mixed text containing emails and the verifier extracts them at no cost; only the verification step uses credits
• Start with a sample — if you are unsure about list quality, verify a small sample first to estimate how many credits the full list will need

API integration tips

• Verify at signup — use the single-email endpoint for real-time verification during registration to catch typos and disposable addresses
• Batch verify on import — when users upload a contact list, submit it as a bulk job and show results when ready
• Use idempotency keys — always include an Idempotency-Key header on bulk submissions to prevent accidental double-charges on retries

Common mistakes

• Verifying the same list twice — the verifier warns you about duplicate submissions, but if you ignore the warning you will spend credits on data you already have
• Ignoring Risky results — these are not safe to send to blindly; review them or exclude them from campaigns with strict deliverability targets
• Not re-verifying old lists — a list that was 95% safe six months ago may be 80% safe today; schedule regular re-checks
• Skipping verification for small lists — even a small list with a high bounce rate damages your sender reputation

When to use Deep mode

Deep mode runs all 25 checks including SMTP mailbox verification and spam trap heuristics. It costs 2 credits per email instead of 1. Select your mode in Step 1 (Prepare) of the wizard before entering emails. Use it strategically:

Use Deep mode for:

• Purchased or rented lists — these often contain dead addresses, spam traps, and recycled domains. SMTP verification catches addresses that look valid but will bounce.
• Important campaigns — product launches, investor communications, or anything where a high bounce rate would be damaging.
• Leads from unknown sources — contest signups, scraped data, or any list where you cannot verify the collection method.
• First-time verification of old lists — if a list has never been verified or hasn't been checked in 6+ months, Deep mode gives you the highest confidence.

Use Quick mode for:

• Routine list hygiene — regular re-verification of lists you've already cleaned.
• Re-verification of recently verified lists — if you verified a list 1-3 months ago, Quick mode catches newly invalid addresses without the extra cost.
• Lists from your own signups — addresses collected through your own forms with double opt-in are generally reliable; Quick mode is sufficient.
• Budget-conscious verification — when you need to verify a large list and want to minimize credit usage.

Trust score nuances

The trust score (0–100) reflects overall confidence in deliverability. A few factors worth knowing:

• Gmail and Yahoo addresses score neutral — they are not penalized or boosted simply for being free providers
• Custom domains with full DNS (MX + SPF + DKIM + DMARC) receive a bonus for having a well-configured mail infrastructure
• Role-based addresses (info@, admin@, support@, sales@) are flagged informationally with no penalty (0 points) — these are standard business addresses; the flag is included for your awareness but does not affect the trust score
• Disposable/temporary domains are flagged as Invalid regardless of other signals
• Unroutable MX IPs (private/reserved ranges like 10.x, 192.168.x, 127.x) trigger a hard fail — the domain cannot actually receive email
• Gibberish local parts (random consonant clusters, mixed random characters and digits) receive a -15 penalty — these are often auto-generated or throwaway addresses
• Plus-addressing (user+tag@) receives a -5 penalty — while legitimate, it can indicate disposable intent in cold lists
• DNSBL-listed domains (Spamhaus DBL, SURBL) receive a -20 penalty — these domains have been flagged for spam or malicious activity
• Young domains (registered less than 30 days ago) receive a -10 penalty — newly registered domains are higher risk for spam and fraud
• Gravatar existence provides a +3 bonus during single email verification — a Gravatar profile suggests a real, active person behind the address (this check is skipped in batch mode for performance)
• Typo suggestions are informational only — if a domain is one character off from a known provider (e.g., gmial.com vs gmail.com), the result includes a suggested correction without affecting the score

Automatic server-level blocking

Verified invalid addresses are automatically blocked platform-wide — even from desktop email clients. When the Email Verifier flags an address as invalid (no MX, disposable, SMTP rejected), it is added to a server-level suppression list. Any attempt to send to that address from Roundcube, Thunderbird, Apple Mail, or any SMTP client will be rejected by the mail server before the message leaves. This protects your sender reputation without requiring manual list cleanup.