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Receiving Error on ESA: 450 4.7.1 Client host rejected: cannot find your reverse hostname,

hashimwajid1
Level 3
Level 3

Hi,

 

we have installed 2 x ESA C190 in cluster. all MX Record, A Record, PTR record is configured on public DNS. now both ESA are in production and sending and receiving emails. 

 

we are facing one issue on ESA1 while sending email to one particular domain on internet. 

for example when i do a telnet to that domain from ESA1 we are getting error

 

on ESA1

 

   telnet example.cisco.com 25 


Trying 1.1.1.1...
Connected to  example.cisco.com.
Escape character is '^]'.
450 4.7.1 Client host rejected: cannot find your reverse hostname, [2.2.2.2 ]
Connection closed by foreign host.

 

ESA2 is working fine 

 

telnet example.cisco.com 25 

 

Trying 1.1.1.1...
Connected to example.cisco.com.

 

even though we have configured Reverse DNS but when i do a SMTP mail test on mxtoolbox for ESA1 we are grtting this error

 

SMTP Valid Hostname Reverse DNS is not a valid Hostname

 

we have configured Reversed DNS but somehow its not working

 

when i do  A record test for ESA1 then its show its ok for ESA1

but when i do SMTP test then its shows Reverse DNS is not a valid Hostname for ESA1

 

i am not able to understand if i do A record test for ESA1 then its show its ok but when i do SMTP test for ESA1 its giving Reverse DNS is not a valid Hostname.

1 Reply 1

Libin Varghese
Cisco Employee
Cisco Employee

The error suggests the destination server is unable to lookup a PTR record for the IP it is receiving the connection from.

 

You may want to confirm there are PTR records published for your public IP used for delivering emails, if already published it could be the destination server having issues looking it up.

 

Regards,

Libin Varghese