[CentOS] sendmail

Mon Oct 2 22:26:20 UTC 2017
Stephen John Smoogen <smooge at gmail.com>

On 2 October 2017 at 18:03, Larry Martell <larry.martell at gmail.com> wrote:
> On Mon, Oct 2, 2017 at 5:29 PM, Stephen John Smoogen <smooge at gmail.com> wrote:
>> On 2 October 2017 at 17:21, Larry Martell <larry.martell at gmail.com> wrote:
>>> I an running CentOS7 in a docker container. I need to send email from
>>> that container so I installed sendmail and then I run:
>>> m4 /etc/mail/sendmail.mc > /etc/mail/sendmail.cf` and when I try and
>>> send mail it fails with:
>>> larry.martll at gmail.com... Connecting to [] via relay...
>>> larry.martll at gmail.com... Deferred: Connection refused by []
>>> Anyone know how I can configure sendmail so that I can send mail?
>> Does this help any?
>> https://stackoverflow.com/questions/26215021/configure-sendmail-inside-a-docker-container
> That post is a bit overwhelming. It has 20+ answers and all are different.
> I have another container running debian buster and in there I do"
> yes yes | sendmailconfig
> and then I can send mail. But I don't see sendmailconfig in CentOS7.
> Is there an equivalent?

Sendmail is not the standard email server for EL7 so I am a bit rusty
here.  The item that caught my attention was the following:

I figured out a way myself, although not the most elegant solution. I
configured the sendmail inside my docker so as to Relay the request
via host's ip. Add the following line to the file "/etc/mail/access

Connect:<host_ip_here>          RELAY
Also, in the host as well as docker, comment out the following line in
the file "/etc/mail/sendmail.mc" by prefixing it with "dnl #" and
suffixing with "dnl".

DAEMON_OPTIONS(`Port=smtp,Addr=, Name=MTA')
I passed the host ip as an environment variable to the docker
container, so that it is configurable. Now the docker's sendmail will
relay it's sendmail's smtp request via host machine.


Beyond that I am not going to be much help as I have not had much
experience with docker.

Stephen J Smoogen.