On 01/19/2018 11:38 AM, Grant Edwards wrote:
I have a /usr/bin/sendmail emulator that transfers mail to an MTA that will then worry about delivery. I need an SMTP server that will relay incoming mail by using that existing command-line utility.
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I need something that accepts mail via SMTP (with SSL and AUTH support), and then relays each received message by invoking a command line utilty that has the same API as /usr/bin/sendmail.
You want (what Sendmail calls) a custom mailer.
There is no local delivery and no acceptance of mail other than via SMTP.
That's probably mostly immaterial. Aside from the fact that you would not add those features if you were write a custom SMTP gateway. Most MTAs will have that, but it can be ignored.
I would very much prefer that there is no queueing: the smtp server should not acknowlege acceptance of the message until the smtp server has invoked /usr/bin/sendmail and it has returned success.
That's possible. But it does add some additional constraints. It also means that traditional MTAs likely won't operate the way that you want this to.
Have you tried putting ssltunnel (or the likes) in front of your existing SMTP server to see if it (they) can handle STARTTLS for you? - Is it possible to augment your existing solution without needing to replace it?
Also, this sounds use case specific enough that I would consider going back to the person maintaining the scrip SMTP server that you're currently using and try to fix it.
-- Grant. . . . unix || die
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