Postfix mail dir issue?

I have a new Webmin/Virtualmin server running and I have an issue with reading/receiving email, sending mail to the server is not bouncing however it is not visible to read either using Webmin > Servers > Read user email (Read User Mail Mail server: Postfix) shows items (e.g. 906 bytes in 5) in the initial summary screen however when you then click through on a specific mail account which shows that there are items to read in the summary screen no email says…

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Can anyone help/advise what is wrong?