Re: [gentoo-user] Re: Simple SMTP to cmd-line MTA relay?

[Grant Taylor]

On 01/19/2018 05:30 PM, Grant Taylor wrote:
> I'm trying to juggle the various pieces as I understand them to see if
> everything can work together.

I have a fleeting thought that /might/ work.  I want to write it down 
before I loose it.

1)  Configure Sendmail's MTA to not have any listening daemon ports.  - 
This means that all interface to the MTA will be via the 
/path/to/sendmail binary.
2)  Configure Sendmail's MSA to listen on TCP port 25.
3)  Configure Sendmail's MSA to smart host (without encryption) through 
your existing SMTP to Exchange gateway.

I /think/ this addresses most parts.

SMTP from ??? connects to the MSA which connects to the Exchange Gateway 
which connects to Exchange via something other than SMTP.  -  I think 
that tracks.

Email from the local machine uses the /usr/sbin/sendmail interface which 
speaks SMTP to the world or a smart host.

I think that does work.  Granted, there are some IPs and or ports to 
juggle to make sure that Sendmail's MSA and your SMTP to Exchange 
gateway don't conflict.  But I think that should be possible to handle.

I don't know if the other common MTAs can do anything like this or not. 
I would hope that they can.

I will also say that it is possible to get Sendmail to do some really 
complex things.  It may be possible to get a single sendmail daemon to 
do everything.  But I think that is going to be more complicated, 
possibly needlessly so if the above recommendation works.

I need to know more details about the different accounts and how they 
interact with msmtp (which I have zero experience with) to know if they 
will play nicely with the above configuration.

The only niggling feeling I have is about 127.0.0.1:25.  Is anything at 
all using that?  I've run across a lot of programs that assume the local 
MTA is listening there.  -  If something is, then it's likely a matter 
of juggling IP(s) and port(s) that various things are listening on.



-- 
Grant. . . .
unix || die