[CentOS] Setting up postfix under CentOS-6

Fri Sep 13 10:56:21 UTC 2013
Timothy Murphy <gayleard at eircom.net>

Ned Slider wrote:

>> I didn't find anything wrong in the document in question
>> (http://wiki.centos.org/HowTos/postfix),
>> except that a couple of packages mentioned
>> (ystem-change-mail*) don't seem to exist in CentOS-6.
>>
> 
> That was for switching the default MTA in EL5. As Postfix is already the
> default in EL6 it is simply not needed.

That's not the case.
If you upgrade from CentOS-5 to CentOS-6,
which I imagine the vast majority of people did,
then sendmail remains the current MTA.
However, this is only a tiny point,
since the document mentions "yum remove sendmail" as an alternative.

>> Firstly, after following the instructions meticulously,
>> I found that I could not send out mail
>> because (according to /var/log/maillog)
>> the From address was
>> tim at localhost.localdomain , and this was
>> rejected by the recipient host or rather his ISP.
>> -------------------------------
>> <tim at localhost.localdomain>  MAIL FROM domain
>> does not exist
>>    (in reply to MAIL FROM command)
>> -------------------------------
>> I cured this by adding
>>    tim tim at gayleard.eu
>> to /etc/hosts .
>> I don't know if this is the best way to go about it?
>>
> 
> This is typically caused by having your hostname set to localhost (or
> loaclhost.localdomain). Your hostname should reflect your fqdn.

If you mean $myhostname in /etc/postfix/main.cf then that is not the cause;
it was set to my fqdn.
Also it is set in /etc/sysconfig/network.
And it is the name given by "uname -a".
I'm not sure where else it can be given?

>> After correcting this, I found my email was still rejected,
>> with the message "Blacklisted by Spamhaus"!
>> I read in <http://www.spamhaus.org/pbl/query/PBL814205>
>> that 'the reason is simply that you need to turn on "SMTP
>> Authentication"'

> The bit at the top of the Spamhaus link says it all really - as a matter
> of *policy*, Spamhaus and/or your ISP has decided that you shouldn't be
> sending email direct from that IP address as it's residential / dynamic
> / whatever. Either way, as a result 90% of the internet is going to
> reject your mail. You will need to relay all outbound email through your
> ISPs smarthost to achieve any sort of deliverability.

Exactly.
So perhaps this should be mentioned in the CentOS document
<http://wiki.centos.org/HowTos/postfix>?

-- 
Timothy Murphy  
e-mail: gayleard /at/ eircom.net
School of Mathematics, Trinity College, Dublin 2, Ireland