This article explains why the error "Source field does not exist. Path=/hmc:Envelope/Content/From/Email/@value." is received when HEAT
Messaging Center is configured to extract the email address from a MAPI incoming email.
Please note this error may show up in HEAT Messaging Center logs or in the Event Viewer logs.
Exchange by default strips the full email address from MAPI header on all internal email and only uses the DisplayName value.