From 6ab143c85698eb84a6765d79a8e119fddc749f0c Mon Sep 17 00:00:00 2001 From: Julien Lutran Date: Fri, 28 Aug 2026 17:44:03 +0200 Subject: [PATCH] nuc: note why its mail path differs from ks2/ks4 (source address, not config) Co-Authored-By: Claude Fable 5 --- nuc/usb4t-dropouts.md | 8 ++++++++ 1 file changed, 8 insertions(+) diff --git a/nuc/usb4t-dropouts.md b/nuc/usb4t-dropouts.md index 4c2898e..1373cca 100644 --- a/nuc/usb4t-dropouts.md +++ b/nuc/usb4t-dropouts.md @@ -82,6 +82,14 @@ zed → mail (bsd-mailx) → /usr/sbin/sendmail = msmtp → mail.lutran.fr:587 ( `zed.rc.orig`. **No credentials in this file** — they live only in `/etc/msmtprc`. +**Why nuc differs from ks2/ks4** (which mail via s-nail straight to +port 25, and work fine): it is not the zed config, it is the source +address. ks4 *is* the mail server's host (internal client, +`mynetworks`); ks2 is a datacenter IP with a PTR. nuc sends from a +**dynamic home IP with no PTR and no SPF alignment**, so the inbound +MX path treats it like any stranger. Hence submission + auth here, +deliberately different from the other two hosts. + Two dead ends worth remembering: - **Port 25 is the wrong port for alerts.** Authentication succeeds,