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Cisco Bug: CSCvu48904 - Enhancement request to provide option to specify hostname/FQDN sent with EHLO/HELO cmds

Last Modified

Aug 31, 2020

Products (1)

  • Cisco Email Security Appliance

Known Affected Releases


Description (partial)

SMTP helo is not matching reverse lookup of IP of interface from which mail sent out.
Due to this some of destination domains categorise this mail as spam.

If ESA is deployed behind LB and NATed IP is seen for sent out mails. 
Reverse lookup of this IP would match NAT'ed hostname while helo sent in SMTP conversation is the interface hostname which would lead the conflict.

This is currently seen with CES deployments with Load Balancer architecture
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