So I do very much the same. In theory, being offline should NOT lose
mail or causes bounces; however you are at the mercy of the sending
servers retry policy as to when re-delivery would be attempted as so I
opted for the two server approach also.
The slight difference is that I've configured things such that the
primary MX is the remote machine (pure MTA) and so it is normal for mail
to be delivered through it ... this way my local machine (combined MTA
and MDA) is able to receive from the general internet but NORMALLY stuff
comes via my remote - it would only receive stuff directly if the remote
was down for some reason.
This is also partly for spam reasons. My spam defences are harder on my
local MDA and it's not been uncommon for spammers to historically target
the secondary mx ...
As to how I test ... basically the same way that you've demonstrated.
HTH
Ian.
On 10/09/2024 05:33, Rhys Woolcott via dorset wrote:
Hi all,
So for the last few weeks I've had some problems with my internet, and
since I host my mail server, I have missed some mail.
Since I'm somewhat of a night-owl, I've decided to setup a `postfix`
server on a remote VM that is configured to recieve any mail sent
while my primary mailserver is "offline".
My query is: Is there a good way for me to test this is working for
external mail and secure without actually taking my primary mailserver
offline?
Thusfar, I've tested with basic SMTP HELO with the following:
```
[root@gltx-rmac-01 ~]# telnet 141.95.90.9 25
Trying 141.95.90.9...
Connected to 141.95.90.9.
Escape character is '^]'.
220 GLTX-SMTP-01.galactix.xyz ESMTP Postfix
HELO example.com
250 GLTX-SMTP-01.galactix.xyz
mail from: t...@example.com
250 2.1.0 Ok
rcpt to: rh...@galactix.xyz
data250 2.1.5 Ok
354 End data with <CR><LF>.<CR><LF>
Subject: This is a test email.
This is a test email, please ignore.
.
250 2.0.0 Ok: queued as A1CC752D1
```
And I do recieve the emails when sent directly this way, but I just
want to verify it's all working correctly for external mail.
Let me know :)
Thanks,
Rhys.
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