If you wish to disable syncing of e-mails sent outside of PersistIQ, simply follow the directions below.
Begin by accessing the Salesforce integrations page in PersistIQ,
Locate Salesforce and click on the Configure button.
On the left side menu, under "Activities", select "Settings".
Un-select the options for, "You or a teammate emails a prospect outside of Persist IQ" and "A prospect replies to an email unrelated to a PersistIQ campaign."
You are all set.