Can I have leads in salesforce not show up in Marketo?

Is this a one time exception or do you typically not want  new leads in SFDC to synch to Marketo?  A one time exception will be difficult if not impossible to implement as all of the lead fields would be visible to the Marketo synch profile and as soon as any of them were updated, the lead would synch to Marketo. 

A possible workaround would be to not add an email address to the Email field in the SFDC Lead record - this will stop a synch from occuring.  You can add the email address to a secondary email field to facilitate searching for the record or sending an email by clicking on the email address in the record.

Thanks, Elliott. This would be a one time exception and when I contacted Marketo support, they spoke of enabling this in salesforce by using something called a private sharing model where the sync user (profile) does not have visibility into the fields. I'll look more into this.  Thanks again. 

Niru,

Marketo supoport is coorect here.  Anything the sync user profile can not see or do will not be shared with Marketo.  It will be best to discuss this with your SFDC admin and outline the accounts you wish not to sync.  They can then build a profile which will allow you to restrict Marketo from syncing those leads which do not qualify for the SFDC Profiles rights. 

Justin Gray

If you don't already have the private sharing model implemented in Salesforce, implementing it may have a significant impact on your organization as users (including the Marketo Synch user) will be able to access only the data they own. No one will be able to view records owned by others unless permissions are made available for non-owners of records using the Role Hierarchy, Group Sharing, etc.  Record owners can grant access for others to specific records they own for otherwise unavailable actions (read, write, transfer).

Since this is a one-time exception, it may not be worth the effort / disruption.  Leaving the email address field empty will accomplish this as a one-off work around.