Problem sending out emails

Linux and Unix-Like Debian
1

Hi,

Our email relay server is a debian server.
The application team in our company regularly receives email alerts from one hpux server (which is routed through the email relay server).
Today we had problems whereby our company's email recipients are not receiving email alerts from the hpux server.

When I checked the logs of our email relay server (mainlog) :

2017-08-20 14:16:53 1djJXZ-000GF4-3D <= exxxxxx@L28bi01.xux.xux.com H=(L28bi01.xux.xux.com) [10.61.1.108] U=root P=esmtp S=575 id=201708200616.v7K6Grl12591@L28bi01.xux.xux.com
2017-08-20 14:16:53 1djJXZ-000GF4-3D ** axxx.kxxxx@x-company.com R=dnslookup T=remote_smtp: SMTP error from remote mail server after initial connection: host sessmg12.x-company.net [1nn.1nn.2nn.nn]: 554 5.7.1 You are not allowed to connect. Please refer to http://ipremoval.sms.symantec.com/ for further information.
2017-08-20 14:16:53 1djJXZ-000GF8-KZ <= <> R=1djJXZ-000GF4-3D U=Debian-exim P=local S=1643 T="Mail delivery failed: returning message to sender"
2017-08-20 14:16:53 1djJXZ-000GF4-3D Completed

I googled for solutions, and the solutions provided was that :

However, when I checked the ip 1nn.1nn.2nn.nn in Symantec's IP investigation page (IP Reputation Investigation), it says that :

How can resolve this problem?

2

You are having problems with Symantec - meaning that you animalware is blocking the connection from HPUX to the mailserver. You can start sendmail on your HPUX box to act as a mailserver for the email leaving that box.

This may be of help -- Sendmail - Configuration - Wiki-UX.info

3

The receiving mail server sessmg12.x-company.net runs Symantec anti-virus/anti-spam and has blacklisted your mail relay server.
You must visit the given Symantec portal and ask for removal from the blacklist.
You mention a HP-UX server. HP-UX by default runs sendmail daemon that unfiltered listens to port 25 i.e. is open for spammers. It must not be reachable from the Internet! Additionally its listener should be restricted to localhost. Then it still can send mails from local users.
AFAIR the instruction for HP-UX:
in /etc/mail/sendmail.cf search for the line

O DaemonPortOptions=...

and add ,Addr=127.0.0.1 to the line.
To activate the new config run

/sbin/init.d/sendmail stop
/sbin/init.d/sendmail start