Exchange 2007 server did not receive email from website


I have an issue that our client did not receive an order email from their website. The web hosting company said the email was failed to deliver to our email server between 10pm and 11pm based on their logs. They said service was unavailable.

How can I troubleshoot this issue? I want to know why the order emails were failed to arrive but the other emails were all fine during that time, according to our mailbox which stores all emails.
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If previously it working fine then you can do message tracking and do the protocol log enabled on Exchange? if yes you can check the log in SMTP received.
EducadAuthor Commented:
Actually the email was identified as a junk email by our MailGuard Filter. How can I do message tracking on Exchange?
mean the your mail gateway blocked that email right? then no need message tracking log since the email not reached exchange server.

Now, you have to configure the mail gateway to trust the incoming mail from the website.

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