HP Instant Capacity User's Guide for Version 9.x

system is on an isolated network, email from the system does not reach HP. This causes your
system to be out of compliance with your Instant Capacity contract if you are using temporary
capacity (TiCAP).
The sendmail application
The sendmail application is used by the Instant Capacity software to send encrypted email
messages from your system to HP. The sendmail daemon, if running, can also be used to receive
email. For purposes of this email configuration, only the ability to send email is required.
Mail applications invoke sendmail to send email. The configuration file, /etc/mail/
sendmail.cf, offers tremendous flexibility.
Overview of email routing across the internet
When the Instant Capacity software uses sendmail to send email to HP, sendmail determines
where it should initially send the email (the first hop). Mail often goes through multiple systems
(hops) before it reaches the final destination. To determine the first hop for the email, sendmail
uses one of the following:
• The email is routed to a mail relay host if it is configured in the /etc/mail/sendmail.cf
configuration file. This is the easiest implementation and can be done with just a one line
change (DS) to the default /etc/mail/sendmail.cf file.
Note that the relay host must be configured to properly route (forward) the email to the
final destination.
• DNS MX records — this method requires that the Instant Capacity system be in an
environment (network) where DNS (Domain Name Server) is operating and properly
configured. sendmail on the system queries a DNS server for the name of the email server
to forward the email to (for the first hop) in order for the email to reach the final destination
(hp.com).
In all cases, the following requirements must be met:
• HP mail servers that receive email expect the host (the mail server in the last hop before
reaching HP) to be properly registered in DNS. If not, the HP mail server rejects, or “bounces”,
the email.
• The From field (email address) in the email message must be known by the receiving mail
server (that is, the hostname is registered in DNS and advertised on the internet). Otherwise,
the receiving mail server at HP rejects the email. This field in the email can be configured
with a simple one-line modification (DM) to the /etc/mail/sendmail.cf file.
In some DNS environments, changes to the default /etc/mail/sendmail.cf file might
not be needed to properly route email from the Instant Capacity system to HP.
• In some environments, configuring your system to properly send email from the system to
HP can require as little as a two-line edit (or none) to the /etc/mail/sendmail.cf file.
In most organizations, configuring mail, including sendmail and DNS configurations, is
usually handled by the IT team.
Example A-1 Example Edit to Sendmail Configuration (/etc/mail/sendmail.cf)
DMmy_company.com
DSmailhub.my_company.com
In this example:
• The Instant Capacity system’s hostname is myICAPsystem.my_site.my_company.com.
• The From field of the email is set to my_company.com rather than to the exact hostname
of the Instant Capacity system. This is because most organizations do not advertise the
names of their internal servers to the internet; however, they do advertise a few (select)
high-level domain names.
A.10 Configuring Email on Instant Capacity Systems 195