[FW-1] Something about Sendmail & FW-1

[Nick Brandson <nickbrandson@FW1-NOSPAMYAHOO.COM>]

Dear guru,

Got some problems with Sendmail setting (I bet).

Having place the Sendmail in DMZ and all the mails CAN
be sent and received successfully and normally EXCEPT
those mails sending to the mail servers or systems
need to do a reversed DNS Lookup, then the user will
receive a bounced back message from the mail server
saying "550.5.71 <receipent's email> ... Relaying
denied. IP name lookup failed [Firewall DMZ Internal
IP]".

Tried to ask the user to add the Reversed DNS record
for the mail server

nslookup x.x.x.x
can receive the reply from mail.x.com
- successful

Firewall settings
1. Mail Servers in the DMZ
2. One-to-one (Static) NAT for mail servers
3. Enabled "Auto Arp" & "Client-side NAT"
4. Rule allow "Any  ->    MailSrvs  ->   SMTP/POP   ->
 Allow"
5. Hide behind this interface 0.0.0.0 for Internal
Segement
6. No Hide mode for DMZ network
7. DNS query is allowed in the Global Property


Internal: 192.168.1.0.x/24
DMZ : 192.168.10.x/24

Firewall-Internal: 192.168.1.254
Firewall-DMZ: 192.168.10.254

Is there any setting has to be done in sendmail
server?

Seems the relay setting is blocked in the sendmail as
it showed the firewall dmz IP address in the error
message...

thanks
Nick

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