I have created a workflow that in fact creates an e-mail if two conditions are there, 1 if the e-mail sent to support@mycompany, and if the subject contains "open a case".
then a case will be created and updated.
No matter who do I send the email from. the message will never go through and always will get stuck and an error message will pop up on Crm server as this one below
#17174 - An error occurred while validating the e-mail message with subject "open a case" in mailbox email@example.com. Microsoft.Crm.Tools.Email.
tion: E-mails for address firstname.lastname@example.org (Sender) in forward mailbox could not be processed as the e-mail address is not associated with any approved forward mailbox user or queue record in CRM.