Before You Import Into Account Engagement (Pardot) or Marketo: Verify the List First

Verify the file before it goes into Account Engagement or Marketo, because both platforms only find dead addresses by mailing them. Account Engagement marks a prospect Undeliverable after one hard bounce; Marketo can set Email Invalid on a hard bounce and leave it there until someone resets it by hand. A trade-show scan list or a data vendor file imported unchecked does its bouncing on your first nurture email, against your sending domain.

Sources, read 2 November 2026: Salesforce Help, Prospect Mailability Status; Adobe Marketo Engage, hard and soft bounces in email and the Marketo Engage glossary.

How each platform reacts to a bounce

	Account Engagement (Pardot)	Marketo Engage
After a hard bounce	Prospect becomes Undeliverable	Email Suspended (24 hours) and, for certain hard bounces, Email Invalid
After soft bounces	Undeliverable at five or more	Soft bounces treated as temporary
Undo	See Salesforce's mailability pages for resetting bounces on a prospect	Email Invalid only resets manually; Adobe says do it only once you've confirmed the address is valid
Mailbox check before sending	No	No

Adobe adds a useful caution: spam filters can produce hard bounces that are "not an indication of the true validity of the person's email address". A bounce isn't always a dead mailbox, and a verifier's result is a second opinion.

Step by step

1. Get the file into one shape. Event platforms, webinar tools and data vendors all name columns differently. The CSV import formatter maps them to clean headers.
2. Merge with what you already have. If the people may already be in Salesforce, export those records too and dedupe; verifying emails in Salesforce covers the round trip without breaking records.
3. Verify the file on the verify page.
4. Split by result:
   • Valid: import as normal.
   • Invalid: don't import them as mailable. If you need the record (a real lead with a phone number), import with Do Not Email in Account Engagement, or a status field you exclude in Marketo smart lists.
   • Risky and unknown: import with a field or list that marks them, and mail them last.
5. First send to the import: valid only. Watch bounces, then add the risky group in a small batch.
6. For Marketo records already flagged Email Invalid, verify them before any manual reset rather than unchecking in bulk.

Why so much of a B2B file comes back risky

Enterprise domains often accept mail for any address (catch-all), so a single mailbox can't be confirmed, and many companies host on Microsoft 365, where single-mailbox answers aren't always reliable; Microsoft's consumer mailboxes (outlook.com, hotmail.com) are similar. Security gateways in front of the mail server add to it. That's normal, and those leads are often real. Why most of my B2B list is risky explains what to send.

Where SimpleVerifier fits

Upload the import file on the verify page; the first 100 checks are free with a Google sign-in. For a Salesforce export, see the Salesforce walkthrough. Pro is $39 a month with the first 100,000 checks a month at full speed, then slower, never cut off. See pricing.