With Soapbox User Integration, you can control who is allowed to register. Leverage your Salesforce Contact data to qualify potential registrants, to make sure the folks registering are the right people.
Allowing only Contacts in Salesforce to register for logged in access
Configure Soapbox User Integration to make sure those registering have an existing Contact in your Salesforce database. This is a great way to limit registration to existing members, or ensure they they pay dues or any registration fees required for registration, as they would then have an existing Contact record.
Why do some users see "This account has been blocked for security reasons..." when registering?
This error message can indicate that Soapbox has run into some confusion when trying to match up the email address they’ve given in the registration process, with what it sees in the Contacts record. This error message is configurable, if you want to provide more detail to the registrant.