A Marketo export is lead data synced with a CRM, carrying scores, program membership and acquisition program. Fields have owners on both sides of the sync, and overwriting the wrong one starts an argument with sales.
Getting the addresses out of Marketo
A smart list with your filters, then Export. The REST API is the better path for anything repeated.
At form submission, so a bad address never becomes a lead. Downstream work fights a bidirectional sync that reintroduces whatever you remove.
What Marketo does with the file you bring back
The import rules decide what a re-import actually changes, which is worth knowing before you upload.
The short version
- List imports deduplicate on email address by default and update the existing lead.
- Email Invalid stays true through an import unless you explicitly overwrite it, which you should think hard about.
- Custom fields import alongside and can hold a verification verdict and date.
- The CRM sync can overwrite fields in either direction, so decide field ownership before importing anything.
The mistake to avoid
Some addresses come back unresolved, and that is a fact about the receiving server rather than a gap in the check. We label those and never bill for them. What that means, and why roughly 28% of business addresses land there, is set out on our page about catch-all domains.
2,300 bounces, of which 800 were bad addresses
Say you import 6,500 trade show scans into Marketo and send the follow-up. The report shows 2,300 hard bounces, which looks like a third of the list is junk. Read the categories before believing that.
Adobe's documentation splits hard bounces in two. Category 1 means the receiving server treated the message as spam or blocked it. Marketo marks the person Email Suspended, holds further sends for 24 hours, and then carries on without any action from you. Category 2 means the address doesn't exist, and that's what sets Email Invalid to true. Suppose 1,500 of your 2,300 are Category 1. Those are people at companies with strict filters, and their addresses are fine. The 800 Category 2 rows are your real data problem.
A check before import would have flagged those 800 and labeled the catch-all domains, which for a B2B badge scan can be a quarter of the file. The 10,000 pack is $25.
Unsubscribe survives a delete, and Email Invalid may not
Marketo has a feature called durable unsubscribe. Behind the visible Unsubscribed field sits a master email status, and when a new person is created, Marketo checks the address against it. Delete someone who opted out, re-import them a year later, and the record comes back unsubscribed. It can't be switched off.
Adobe's page on the feature notes that it looks only at the standard Unsubscribed field. Don't assume Email Invalid gets the same protection. If your team's habit is to delete dead leads to keep the database under its contracted size, a later list import of the same addresses can create them clean, and the first send rediscovers every one.
Keep invalid addresses in a static list that your import process checks against, or hold the verdict in a custom field on a slim record. Marketo contracts are usually sized by database records, so look at yours before deciding how many dead leads are worth keeping for the memory alone.
Questions people ask
Where should verification sit in a Marketo setup?
At the form, so a bad address never becomes a lead. Downstream cleaning fights a bidirectional CRM sync that will keep reintroducing whatever you remove.
How should catch-all results be handled in B2B?
Store the verdict in a field and exclude them from the first touch of a cold program. They are roughly 28% of B2B addresses and cannot be confirmed by anyone.
Does verification help with the CRM sync?
It gives both systems a shared field to act on. Without it, marketing and sales each form their own opinion about whether an address is good.