MailScanner: Could not analyze message

[Am Am]

Hi,
Mailscanner is not sending outbound mails for a domain and send it to quarantine.In the default mail account, we get a mail, like a bounce back mail, with the following content:
This message has been rejected. The filters said this:
Report: MailScanner: Could not analyze message
.
Since there aren't any further details mentioned, I don't know where to look.So please help me with this and let me know how to fix it.
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