Clean your Marketo database - and shrink what you pay for
Marketo flags a lead as Email Invalid the moment it hard-bounces and stops mailing that address - but it can't judge a lead it has never sent to, and on a plan billed by database size those never-verified records cost you twice: in deliverability and at renewal. Qualisend closes that gap: connect Marketo to verify any static list (or verify a smart-list export), then suspend or delete the dead records so junk never reaches a send - or your invoice. The CSV loop, the API and no-code options below work too.
Connect Marketo directly, no CSV needed
Connect with an API key
Enter your Client ID and Client Secret (Admin → Integration → LaunchPoint) and REST endpoint (Admin → Integration → Web Services). Then add a qualisendStatus lead field in Field Management.
- Clean the leads in any static list
- Results saved in a custom field on each lead
- New leads checked in real time via webhook
- Auto-clean every 7, 14 or 30 days
Prefer CSV or the API? Both work too, see below.
What Marketo cleans for you
Marketo's native hygiene centers on one field: Email Invalid. When a lead hard-bounces, Marketo sets that person's Email Invalid field to true, records an Email Invalid Cause, and stops sending marketing email to the address - and because it's an ordinary field, you can build a smart list that returns every invalid lead in the database. A separate Marketing Suspended field lets you bench an address without deleting the record. For addresses Marketo has actually mailed, that's real, automatic hygiene.
What it can't catch
The catch is that every one of those mechanisms is reactive - it needs a send and a bounce to fire. Never-mailed invalids from list buys, event-badge scans, and other automation platforms, plus old form fills and signup typos, have never bounced because they've never been sent to. Disposable addresses, role addresses, and decayed B2B mailboxes - the first.last@company.com that converted last year and became a hard bounce the day that person changed jobs - all look perfectly healthy in Marketo today. An imported list is the sharpest case: it arrives with its bounce history stripped, so addresses that were already failing on the old platform look brand new - and each one lands in the database you're billed on.
Why a clean Marketo list matters
On Marketo the stakes are double, because most Marketo Engage agreements are priced on database size. A dead lead is a line item on your invoice as well as a drag on deliverability - and the trap is that neither Marketo's own Email Invalid flag nor a Marketing Suspended lead removes the record, so both keep costing you until you delete. Meanwhile that never-verified address is what a mailbox provider meets first: your opening campaign is where Gmail and Yahoo's bounce and complaint thresholds, and Marketo's own engagement scoring, form their impression of your domain. Cleaning before a send does two jobs at once - it can pull you under a database tier at renewal, and it protects the inbox placement of the programs that actually convert.
Prefer CSV or the API? Here's the manual path
The native connector is the fastest route, but the CSV loop works on any Marketo plan: export from Marketo, verify in Qualisend, and act on the results.
Build a smart list and export from Marketo
In your Lead Database, build a smart list for the segment you want to clean - everyone, a single acquisition source, or one program's members - and export the view to CSV with the email column. For a maintenance pass, a smart list that excludes leads already flagged Email Invalid keeps the file down to just the unknowns.
Verify the file in Qualisend
Upload the CSV to Qualisend bulk cleaning - up to 1,000,000 addresses, duplicates charged once - or paste addresses directly. The free plan's 100 credits cover a first sample.
Read the results
Every address returns deliverable, risky, undeliverable, or unknown with a reason code and a 0-100 score, plus sub-flags (catch-all, disposable, role, full mailbox) and the MX provider and probe detail as evidence. Download the cleaned CSV.
Suspend or delete the dead leads in Marketo
Re-import the cleaned file to populate a custom field like Verification Status, or match on email to set Marketing Suspended on the undeliverables. Suspending stops every marketing send immediately, but the record still occupies your billable database; deleting the genuinely dead records is what actually shrinks your database-size count - save the verified CSV as your archive first.
Or automate it at signup
Prefer to keep junk out from the start? Verify at the point of capture with the Qualisend REST API (scoped keys, rate limits, webhooks), or wire a no-code flow through Zapier, Make, or n8n so a new form fill or synced lead is checked before it ever becomes a billable Marketo record - no typo or disposable address gets in to bounce on the first campaign.
What Qualisend flags on every address
- Never-mailed invalids from imports, list buys, and event scans that would hard-bounce and flip Email Invalid on your next campaign
- Decayed B2B mailboxes - a lead who changed jobs since import looks healthy in Marketo until the send bounces
- Disposable / throwaway domains dropped into a gated-content form to grab the asset
- Role addresses (info@, sales@) that skew Marketo's engagement scoring and behavioral triggers
- Catch-all domains, flagged so you can build a dedicated smart list and throttle them
- A 0-100 confidence score and machine-readable reason code on every address
The native Marketo connector is live. Connect it in Qualisend under Integrations and work with your Marketo list directly, no CSV needed.
What to do with each result
Every address comes back with a verdict and sub-flags. Here's the action that keeps your Marketo list clean without throwing away contacts you can still reach.
deliverableKeep mailing as normal.deliverable + role flagKeep for account and transactional touches; exclude from engagement-scored programs.risky + catch-all flagMove to its own smart list and throttle - a catch-all accepts everything at the door, so a single send proves little.risky + disposable flagSet Marketing Suspended - the inbox was built to expire.unknownKeep active and re-verify next clean - usually greylisting or rate-limiting, not a verdict on the mailbox.undeliverableSuspend or delete; on a database-size plan, delete the genuinely dead to take them off your billable count. Don't wait for the bounce to set Email Invalid for you.Related reading
The full step-by-step: export a smart list, verify, and suspend or delete the dead leads.
Cleaning is half of deliverability - authenticate your Marketo sending domain too.
Verify at capture so junk never becomes a billable Marketo record.
How fast a dirty list compounds into a deliverability problem.
Why your first campaign to unverified leads sets the mailbox provider's impression.
A cadence for maintenance cleans sized to how your database grows.
Related integrations
Keep your Omnisend audience clean, deliverable, and off your bill
Keep your Emma audience clean and off your Active-contact bill
Keep your Braze audience clean before the first send bounces
Keep your Iterable audience clean before it costs you an MAU
Keep your Bloomreach audience clean before the campaign fires
Keep your CleverTap audience deliverable before the campaign fires, not after the bounce
Marketo verification FAQ
Clean your Marketo list in minutes
Start free with 100 credits that never expire - no card required. Connect, verify, and protect your next campaign.