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Install of SMTP mail transport

1.  Introduction

We need to have a minimal mail service on the cluster and grid nodes, to be able to collect logs, error reports etc. To do this without too much configuration, we use an STMP mail relay (Postfix) on GridVM, and a simple SMTP client (sSMTP) on the other systems. All the mail is then delivered to, which takes care of the forwarding etc.

We use a PostFix relay on GridVM, instead of just sSMTP everywhere pointing directly to, to have some spooling in case physics is unreachable.

2.  SMTP mail relay on

I've configured to accept mail for the grid hosts.

gridvm:/etc/postfix/ :

mydestination =,,, ...

3.  SMTP mail relay on GridVM

Note that SMTP is only open to the local networks, so that we don't have to worry about external traffic (also in iptables).

In this configuration with local_transport pointing to smtp:, all mail is sent to the relay host. Note also that in this way the /etc/aliases on gridvm is ineffective.

gridvm:/etc/postfix/ :

relayhost = []
inet_interfaces = localhost,
mynetworks =,,
mydestination =
local_transport = smtp:[]

4.  SMTP mail client on CEs, UIs and WNs

We use sSMTP, a very simple SMTP mail client that is only able to forward the mail to a relay, and only do minimal adjustments. I've chosen sSMTP over other solutions because it's supported by the Debian project (many simple clients aren't well supported(, it only needs a minimal configuration and no large daemons (contrary to using Sendmail/Postfix/Exim), and is available as an RPM that "provides" sendmail, so that one can uninstall the existing MTA package without running into an RPM dependency problem.

See for a nice article about it.

/etc/ssmtp/ssmtp.conf :

# The person who gets all mail for userids < 500
# Make this empty to disable rewriting.
# The place where the mail goes. The actual machine name is required
# no MX records are consulted. Commonly mailhosts are named
# The example will fit if you are in and your mailhub is so named.
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Page last modified on March 27, 2009, at 03:04 PM