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Platform-specific, because the thresholds, the warnings and the consequences are not the same in any two of them.

Clean a list for ActiveCampaign

ActiveCampaign bills per contact across all lists, so a dead address costs as much as a customer. Clean the list before import, from $5 per 1,000.

Clean a list for Amazon SES

Amazon SES has no list and no import step, and its 5% bounce review threshold counts from your first send. Verify in your app before mail goes out.

Clean a list for AWeber

AWeber bills per subscriber and counts an address once across lists, so a dirty import costs you in bounce rate, not a double bill. Clean it first.

Clean a list for Braze

Braze users arrive through your SDKs, not a CSV, so check email inside your app. A hard bounce leaves 1 thing unchanged: the subscription state.

Clean a list for Brevo

Brevo bills on emails sent rather than contacts stored, so an unverified list costs you send volume and reputation rather than a higher storage tier.

Clean a list for Campaign Monitor

Campaign Monitor bills each client separately and counts an address once for every list it is active on. Merge, dedupe and verify before you import.

Clean a list for Constant Contact

Constant Contact bills on the highest active contact count in a billing cycle, so imports that bounce still cost you. Verify old member lists first.

Clean a list for ConvertKit

ConvertKit, now Kit, bills each subscriber once however many tags they carry. Verify before a migration and after a lead magnet, which draws throwaways.

Clean a list for Customer.io

Customer.io keys people by your own ID with email as an attribute, and workflows fire within minutes. Validate in the signup handler, before identify.

Clean a list for Drip

Drip bills per person and syncs from your store all day, so verify at the point of capture. A once-a-quarter list clean misses 3 months of typos.

Clean a list for Elastic Email

Elastic Email reviews large imports on new accounts, and a suspension there is quick and total. Verify a list before it ever reaches the platform.

Clean a list for Emma

Emma audiences are long-lived alumni, member and donor lists whose work and campus addresses decay fast. Verify once a year and before any appeal.

Clean a list for GetResponse

GetResponse holds large imports for manual review and asks how you collected them, and an address on two lists counts as two contacts. Dedupe and verify.

Clean a list for HubSpot

HubSpot bills by marketing contact, so import records as non-marketing, verify them, and promote only the deliverable ones. The bounced flag persists.

Clean a list for Iterable

Iterable takes users from your product and warehouse through its API, so verification belongs in the pipeline that writes user records, not before a send.

Clean a list for Klaviyo

Klaviyo bills on active profiles and syncs from your store all day, so checkout typos get billed and mailed. Verify before import and on a schedule.

Clean a list for Mailchimp

Mailchimp bills for every contact in your audience, deliverable or not, and judges a new list on its first campaign. Verify the file before you import it.

Clean a list for MailerLite

MailerLite approves new accounts by hand and asks where your list came from. It bills by subscriber, so arrive with a verified list and a consent record.

Clean a list for Mailgun

Mailgun does not check addresses on the sending path, so an address reaches your suppression list only after a real bounce. Verify at capture in your app.

Clean a list for Mandrill

Mandrill has no contact list because addresses come from your own database. Verify at registration, and watch the Mailchimp account that shares its risk.

Clean a list for Marketo

Marketo syncs both ways with your CRM, so whatever you remove can come straight back. Verify at form submission and write the result to a shared field.

Clean a list for Moosend

Moosend bills each unique address once across all your lists, but bounce status is kept per list. Dedupe and verify in one pass before you consolidate.

Clean a list for Omnisend

Omnisend bills subscribed and non-subscribed contacts alike; only unsubscribed ones are free. Verify checkout and SMS-only contacts before emailing.

Clean a list for Pardot

Pardot prospects sync to Salesforce leads and contacts, so a deleted prospect is recreated by the sync. Store the verification result in a field instead.

Clean a list for Postmark

Postmark keeps no marketing list and holds suppressions per message stream. For transactional mail, verify at signup, before the address is stored.

Clean a list for Salesforce Marketing Cloud

Marketing Cloud imports into data extensions, so a verification result becomes one more attribute for a send filter. Deleted rows return on the next run.

Clean a list for SendGrid

SendGrid does not check addresses before it sends, and suppressions are kept per subuser. Verify at signup, while the person can still fix a typo.

Clean a list for Sendinblue

Sendinblue and Brevo are one product, so imports behave the same and blocklisted addresses stay blocked account-wide. Verify an old list before relaunch.

Clean a list for SparkPost

SparkPost is API-driven with no real contact list, so verify where addresses enter your system. Read bounce codes before seeding its suppression list.

Clean a list for Zoho Campaigns

Zoho Campaigns syncs with Zoho CRM, so an imported list becomes CRM data and a verification verdict is most useful as a field both systems can read.

Email Validation in JavaScript

Validate email in JavaScript three ways: the HTML5 email input, a short regex, and a server-side API call that checks the mailbox. Working code for each.

Email Validation Regex: Patterns That Work

Copy-paste email regex for JavaScript, Python and PHP, the 254-character limit, and the SMTP check that proves a mailbox exists after the pattern passes.

Fix ActiveCampaign bounce rate

ActiveCampaign sets a contact to Bounced on one hard bounce or after a soft bounce threshold you can configure, and it reviews accounts that stay above 2%.

Fix Amazon SES bounce rate

Amazon SES puts an account under review at a 5% bounce rate and may pause all sending at 10%. Only permanent bounces count, over its own rolling window.

Fix AWeber bounce rate

AWeber marks a subscriber undeliverable on a hard bounce or after a run of consecutive soft bounces. Most accounts have never checked that threshold.

Fix Braze bounce rate

In Braze a hard bounce marks the address invalid but leaves subscription state alone, so strong push numbers can hide an email problem for months.

Fix Brevo bounce rate

Brevo blocklists a hard-bounced address across your whole account, not per list, and reviews new accounts by hand. Its guidance is hard bounces under 2%.

Fix Campaign Monitor bounce rate

Campaign Monitor reports bounces per client, so an agency has to check each one separately, yet one client's bad list can draw a review of the whole login.

Fix Constant Contact bounce rate

Constant Contact sorts bounces into 6 types, and only Non-existent address removes the contact on its own. Start there to bring your rate down.

Fix ConvertKit bounce rate

ConvertKit records a bounce on the subscriber and stops every sequence at once. Its cold filter finds the unengaged, not the dead. Find both here.

Fix Customer.io bounce rate

Customer.io sends from always-on workflows, so bounces arrive as a steady trickle that never spikes. Read the per-person activity log, not only the rate.

Fix Drip bounce rate

Drip sends from behavioral workflows, so a bad address from a store integration can sit in several at once. Fixing the broadcast list does not stop them.

Fix Elastic Email bounce rate

Elastic Email pairs low prices with strict account review, and it suspends senders for bounce rates that a more expensive platform would only warn about.

Fix Emma bounce rate

Emma suppresses a hard bounce at the audience level, so one department's bad send stops mail from every sub-account sharing that audience.

Fix GetResponse bounce rate

GetResponse reviews large imports by hand, so a bounce problem often shows up first as a held import. It treats bounce rates above 2% as a warning sign.

Fix HubSpot bounce rate

A hard bounce in HubSpot sets Marketing email bounced on the contact and blocks marketing mail for good. Clearing 1,000 flags in bulk brings it back.

Fix Iterable bounce rate

Iterable writes a bounce to the user profile and unsubscribes that user from email. Most sends run through journeys, so 1 report won't show them.

Fix Klaviyo bounce rate

Klaviyo suppresses hard-bounced profiles with a recorded reason and treats a rate above 2% as a risk. Its deliverability score also blends in engagement.

Fix Mailchimp bounce rate

Mailchimp moves hard-bounced addresses to Cleaned and suspends accounts instead of warning them. Sort the Cleaned list by date to find the import at fault.

Fix MailerLite bounce rate

MailerLite approves every new account by hand, weighing your list source, and can decline it. It expects bounces under 2% and watches new senders closely.

Fix Mailgun bounce rate

Mailgun keeps the full SMTP conversation for each bounce, so you can tell a 550 no such user from a 550 policy block. Pull the logs before retention ends.

Fix Mandrill bounce rate

Mandrill runs under a paid Mailchimp account and shares its compliance review, so 1 suspension on the marketing side can stop transactional mail.

Fix Marketo bounce rate

Marketo sets Email Invalid to true on a hard bounce and stores the receiving server's message in Email Invalid Cause. The flag syncs to your CRM for sales.

Fix Moosend bounce rate

Moosend records bounces per mailing list, not per account, so the same dead address can stay live on another list. Check every list, not only one.

Fix Omnisend bounce rate

Omnisend marks only the email channel non-mailable after a hard bounce while SMS and push keep running, so blended metrics look healthy as email fails.

Fix Pardot bounce rate

Pardot, now Account Engagement, marks a prospect undeliverable after a hard bounce or repeated soft bounces, and sales sees it on the Salesforce record.

Fix Postmark bounce rate

Postmark tracks bounces per message stream and publishes distinct types such as HardBounce, Transient and Blocked. Branch on each type in your code.

Fix Salesforce Marketing Cloud bounce rate

Marketing Cloud stores bounces in the _Bounce data view with a category, a subcategory and the SMTP reason. The tracking summary shows none of it.

Fix SendGrid bounce rate

SendGrid keeps Bounces, Blocks, Invalid Emails and Spam Reports as separate suppression lists. Only the Event Webhook delivers bounces in real time.

Fix Sendinblue bounce rate

Sendinblue is the former name of Brevo and runs on the same platform, so a hard bounce blocklists the address account-wide. Current help is under Brevo.

Fix SparkPost bounce rate

SparkPost, now part of Bird, gives every bounce a numeric classification code that separates invalid recipients from policy blocks. Read codes, not totals.

Fix Zoho Campaigns bounce rate

Zoho Campaigns reviews new accounts and large imports by hand and refuses purchased lists, so a poor list usually surfaces as a held campaign.

How to Stop Fake Email Signups in Shopify

Stop fake Shopify signups: verify each new customer email with a webhook or a Zapier step, tag the result, and unsubscribe fakes before your next campaign.

How to Stop Fake Signups in Klaviyo

Stop fake email signups in Klaviyo: verify each new subscriber, tag the result on the profile, and suppress invalid and throwaway ones before a send.

How to Verify an Email With Telnet

Verify an email by hand with telnet: find the MX record, open port 25, send EHLO, MAIL FROM and RCPT TO,, then read the 250 or 550 reply code.

How to Verify Apollo Leads Before You Send

Check an Apollo export before a sequence: export the CSV, run a live SMTP check, split valid from catch-all, and load the safe rows, from $5 per 1,000.

How to Verify Clay Leads Before You Send

Verify Clay leads before a sequence: export the table, run one live SMTP check per address, and send only valid rows. Checks start at $5 per 1,000.

How to Verify Cognism Leads Before You Send

Verify Cognism leads before outreach: export the list, check each mailbox live, and keep your data trail short with a 30-day default retention window.

How to Verify RocketReach Leads Before Sending

Verify RocketReach leads before a sequence: check every address in the export, pick one work email per contact, and skip invalid rows. From $5 per 1,000.

How to Verify ZoomInfo Leads Before Sending

Check a ZoomInfo export before outreach: dedupe across territories, run a live SMTP check, group catch-all domains by account, and budget by tier.

Stop Fake Signups on HubSpot Forms

Add email verification to HubSpot forms with a Zapier step or an API call, store the result on the contact, and keep fake signups out of your lists.

Switching From BriteVerify: Step by Step

Move from BriteVerify to ZapBounce: split its risky result into catch_all and unknown, swap form and bulk checks to the API, then re-check lists.

Switching From Hunter Verification, Step by Step

Move verification from Hunter to ZapBounce: map six Hunter statuses to four results and three flags, swap the API call, and keep credits that never expire.

Switching From Kickbox: Step by Step

Move from Kickbox to ZapBounce: spend down your credits, map Sendex rules to results and flags, swap the API call, and buy credits that never expire.

Switching From NeverBounce: Step by Step

Move from NeverBounce to ZapBounce: map five result codes to four, swap the API call, move bulk jobs and webhooks, then re-check old lists.

Switching From ZeroBounce: Step by Step

Move verification off ZeroBounce: export results, map seven statuses to four results and three flags, swap the API call, and pay $5 per 1,000 checks.

Verify Google Maps Scraped Leads Before Sending

Verify Google Maps leads before outreach: dedupe the export, check each mailbox live, and sort role and free-provider addresses. From $5 per 1,000.

Verify LinkedIn Sales Navigator Leads

Verify the emails on a Sales Navigator lead list before outreach: check the finder's output with a live SMTP test and flag catch-alls.

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100 free checks a month, no card, and the unknowns come back labeled.

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