Account Name and Contact Name do not populate from Email-to-Case in Salesforce

This behavior occurs for one of three reasons. Review each scenario below and apply the appropriate fix:

• The email did not match any Contacts — Perform a global search for a matching contact in Salesforce. If none exists, create a new Contact with the correct email address.
• The email matched more than one Contact — Change the email address on the duplicate contact records so that no single email address is associated with more than one contact.
• The inbound Email-to-Case SOSL query returned multiple results — When Email-to-Case processes an inbound email, Salesforce performs a SOSL (Salesforce Object Search Language) query to find a Contact with a matching email address across both standard and custom Email fields on the Contact object. If more than one Contact matches, no contact will be related to the case. Audit your Contact records to ensure email addresses are unique across all email fields.