The Postfix program in Microsoft Forefront Online Protection for Exchange (FOPE) generates many deferrals on email messages that are sent to a mail server if the mail server is deployed behind a Cisco PIX firewall device.
FOPE uses the Postfix program for mail delivery. This issue occurs because of an issue in the software of some older Cisco PIX firewall devices. This issue causes email messages to be deferred when the messages are sent to a mail server that is behind the device.
To work around this issue, disable the fixup protocol for SMTP in the Cisco PIX firewall. To do this, use the following fixup protocol command:
no fixup protocol <protocol> <port>
For more information about the fixup protocol commands, see the Cisco documentation.
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