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

[Grant Edwards]

On 2018-01-19, Ralph Seichter <m16+gentoo@×××××××××××.net> wrote:
> On 19.01.18 19:03, Grant Edwards wrote:
>
>> I need to setup an SMTP relay server.
>>
>> It needs to accept messages as an SMTP server (using SSL and AUTH on a
>> non-standard port) from a single user and single source and then relay
>> them by passing them to a command-line MTA (e.g. /usr/bin/sendmail
>> replacement provided by msmtp).
>
> Based on your description you seem to have things backward.

I want to accept incoming email via SMTP (my computer is an SMTP server).

I want to relay each of those messages by invoking a command-line
utility that has the same "API" as /usr/bin/sendmail.  That utility
injects the mail into another machine's MTA.

> Sendmail is used to inject mail into an MTA on the local machine,
> and the MTA can then use SMTP to transfer said mail to another
> server.

In this case, the /usr/bin/sendmail utility transfers the message to a
different machine's MTA using mechanisms that are beyond the scope of
my question.

> If the final recipient (i.e. mailbox) is on the same server the mail is
> generated on, the MTA can use a local transport mechanism to store mail
> instead of passing it on via SMTP.

There is no local delivery.  It is a relay that accepts mail via SMTP
and transfers it to a different MTA.  The usual way to do this is to
accept mail as an SMTP server and then relay it to the next MTA by
acting as an SMTP client (e.g. via postfix's 'relayhost' setting).

Instead of transfering mail to the next MTA by acting as an SMTP
client, I want to transfer it by invoking a command-line utility like
sendmail or msmtp.
     
> I suggest you clarify your goal, and ask on the Postfix mailing list
> (or Exim, etc.) for more information.

Will do.

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