CentOS - Oct 2018 - Setting up sendmail to mail system messages on CentOS 6 and 7

Hi all,

I've previously configured sendmail to send system messages on selected
servers running CentOS 6. Usually they just kinda' work out of the box. No
problems to speak of.

However most of my CentOS 7-servers are rather flakey when it comes to
sendmail. Most of the time they just won't send mails for whatever reason. 
Further, most of the time I can get it working, it's usually about a
firewall rule not set, the firewall not having been reloaded or some simple
such.

There is however this one server that just won't play along.
Daemons are up and restarted to pick up any changes, hostnames set etc. but
still nothing. 
I'm at wits end with this one.

Here is a typical guide I've used for CentOS  6, and that I've used for
the
problem server above as well as for other CentOS 7-machines.
<https://www.jeffgeerling.com/blogs/jeff-geerling/configure-sendmail-centos>

Is setting up sendmail different on CentOS 7 in any way, as compared to
CentOS 6??
Anything else I should double-check?

-- 
BW,
	Sorin
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Am 26.10.2018 um 14:44 schrieb Sorin Srbu:
> Here is a typical guide I've used for CentOS  6, and that I've used
for the
> problem server above as well as for other CentOS 7-machines.
>
<https://www.jeffgeerling.com/blogs/jeff-geerling/configure-sendmail-centos>
That "guide" is not really useful nor clever. In a scenario like
yours,
you would setup Sendmail as a nullclient. That's documented in 
cf/README. Or even drop Sendmail and choose a software like msmtp or 
ssmtp which is dedicated for such purpose. You don't need the MTA 
functionality of Sendmail.
> Is setting up sendmail different on CentOS 7 in any way, as compared to
> CentOS 6??
Not really.
> Anything else I should double-check?
Your logs will tell you what is happening and where to look at closer. 
If you like to get specific help from this list I feel you should 
provide your sendmail.mc and log content demonstrating your issue(s).

Alexander

> -----Original Message-----
> From: CentOS <centos-bounces at centos.org> On Behalf Of Alexander
Dalloz
> Sent: den 26 oktober 2018 16:05
> To: centos at centos.org
> Subject: Re: [CentOS] Setting up sendmail to mail system messages on
> CentOS 6 and 7
> 
> Am 26.10.2018 um 14:44 schrieb Sorin Srbu:
> > Here is a typical guide I've used for CentOS  6, and that I've
used for
the
> > problem server above as well as for other CentOS 7-machines.
> >
<https://www.jeffgeerling.com/blogs/jeff-geerling/configure-sendmail-
> centos>
> 
> That "guide" is not really useful nor clever. In a scenario like
yours,
> you would setup Sendmail as a nullclient. That's documented in
> cf/README. Or even drop Sendmail and choose a software like msmtp or
> ssmtp which is dedicated for such purpose. You don't need the MTA
> functionality of Sendmail.
I'll look those up. The suggestions makes a lot of sense.

> > Is setting up sendmail different on CentOS 7 in any way, as compared
to
> > CentOS 6??
> 
> Not really.
Thanks.

> > Anything else I should double-check?
> 
> Your logs will tell you what is happening and where to look at closer.
> If you like to get specific help from this list I feel you should
> provide your sendmail.mc and log content demonstrating your issue(s).
Gotcha'.

This morning I found a <bleep>load of "This message hasn't been
delivered
yet" mails in my inbox.
Turns out the central uni mail filter had intercepted all my test mails from
the very beginning.

Previous log messages stated the mails had been accepted for delivery from
the mail servers and I took their word for it.

What I missed was these messages that came in slightly later; "First-time
sender tempfailed as anti-spam measure; please try again in 720 minutes..."

I'll have a talk with the central support and see if they can't ease up
on
this.

Thanks everybody for your assistance as well as suggestions!

--
//Sorin