Issue with account not creating tickets

We use the email connector for all of our clients and have no issue when clients email our support address which will generate a ticket for them and forward the email to the client.
But for one customer whenever they email our support address no support ticket email is generated and we need to input the ticket manually.

I checked all settings on the account, the main contact email field only has the domain.com address in it.

Thanks in advance

Please use the Help > Technical Support menu in RangerMSP, and Outlook, to email us your RangerMSP log files for analysis.

Important: In your email please specify the exact email address the customer sends from (not only the domain).

Thanks.