How could you create conversations from our internal clients from same domain mail ?

Hello there,

we have external clients which is easy to create conversations. But we have also internal clients who have the same domain mail than the universal inbox (support@kesselmedia.fr) and these clients who are not operator, have some questions to ask also (they have an email @kesselmedia.fr. How could they create conversation, whithout being operator, but using support@kesselmedia.fr like a normal client ?

Best regards,

Ludovic