Issue Description
You may have received an alert from Salesforce informing you of End of Life for TLS v1.0 and 1.1 as of September 2019

Issue Resolution
Marketo Supports TLS encryption v1.2, and is fully ready for Salesforce End of Life of versions 1.0 and 1.1

https://www.marketo.com/company/trust/security/

Who This Solution Applies To
Salesforce Administrators