Not able to send mails from sendmail

I am not able to send mails from sendmail, in the log file i found the error: “Connection reset by” . we are using centos 5.9 server and google domain for emails.

in mailq i could see another message like " (reply: read error from"

Please help me in this issue.


once try telnet to

#telnet 25

Only doing a telnet to on port 25 will solve the problem? I don’t think so, and I am sure he needs to add TLS authentication to Sendmail configuration to allow and sending mails from box…What you say I am right?

I am getting this message when i telnet

Connected to (
Escape character is ‘^]’.
Connection closed by foreign host.

When i add TLS authentication, i could see this “did not issue MAIL/EXPN/VRFY/ETRN during connection to MTA” in /var/log/maillog…


Yes, but just for conformation whether he able to connect to or not


once look at my screenshot while i’m trying telnet to

Yes, i tried from different server which is not there in our network. I could see the output as same.
Seems there is an issue with our firewall or network setting. But we didn’t have this issue in last week also, all of sudden it has come.
I will analyse the things in my LAN.


Thats great and also once check the dns records for your host, does your server have dns records

#nslookup serverip

i have checked for DNS records. we do not have any dns configured. that works from our hardware firewall.
But the mail log says that ", dsn=4.0.0, stat=Deferred: Connection reset by". confused where to start working on this…