[ale] SMTP recommendation?

[DJPfulio at jdpfu.com]

I think postfix only cares if you use authentication for the end-user address.  If you have trusted systems that don't need to be authenticated to send, then you can make the "FROM" and reply-to anything you like.  Thunderbird has an "identities" setting to do this.

The way I do it is by never allowing senders from my domains to send from outside the approved systems.  So JDPfu.com email can only originate from systems inside the LAN.  The email gateway, running postfix, doesn't access any authenticated email - just server-to-server stuff on port 25/tcp.  Then, another system inside does all the IMAPS and SMTPS stuff for LAN clients.

I run the email-gateway in an LXD container. Works well. Very fast, but it is bloated, since it runs Ubuntu 20.04.3 LTS - cloud image. Ubuntu is sorta bloated in the cloud image area. 
 
$ df -Th
Filesystem           Type      Size  Used Avail Use% Mounted on
lxd/containers/spam1 zfs        11G  1.8G  9.2G  17% /

It definitely isn't alpine.  Hummmm Bet I could get alpine to use less than 300MB.

But there are 50 different ways to solve this, I'm sure.



On 12/6/21 5:48 PM, James Sumners (ALE) via Ale wrote:
> It’s been many years since I’ve dealt with setting up an SMTP server
> to actually send mail all over the Internet. But I find myself in a
> bit of an annoyance with my mail provider. The short version is they
> support an incoming catch all feature that will deliver mail for any
> unrecognized recipient to a designated mailbox, e.g. for
> foobar at example.com <mailto:foobar at example.com>, “footer” isn’t a
> known recipient so that mail will be delivered to
> catchall at example.com <mailto:catchall at example.com>; but they do not
> support _sending_ as any sender. I use this catchall to register
> accounts, e.g. amazon at example.com <mailto:amazon at example.com> or
> some-random-site at example.com <mailto:some-random-site at example.com>,
> so that I can see exactly who has decided to ignore my opt-out
> preferences or is selling my email address. But sometimes I need to
> send an email as that identity so that I can get support, and my
> provider isn’t supporting it. So I want to setup my own SMTP server
> that only sends mail and will send as any sender for the domain I
> have configured as the allowed domain.
> 
> I suspect Postfix is the appropriate tool, but am open to any of them
> (e.g. exim). But what would you use? Are you able to provide a
> minimal example configuration?
> 
> Ideally I would run this process in a Docker container and do TLS
> termination at my existing HAProxy instance.
>