[PLUG] No Incoming Mail: Postfix-2.11.3 [RESOLVED]

Keith Lofstrom keithl at gate.kl-ic.com
Thu Jan 8 22:57:31 UTC 2015


On Thu, Jan 08, 2015 at 10:55:18AM -0800, Rich Shepard wrote:
> On Thu, 8 Jan 2015, Rich Shepard wrote:
> 
> >  Anyone with ideas, suggestions, and advice please call 503-667-4517 to
> >share them with me.
> 
>   Never mind. I _think_ it was power-cycling the firewall/router and DSL
> modem/switch that fixed the problem. That makes no sense to me because I was
> able to load web pages all the time there was no incoming mail.
> 
>   Rather than calling, if any of you postfix gurus have thoughts on what
> might have halted smtpd seeing incoming mail after the logs rolled over at
> 04:40 and why restarting postfix a couple of times then power-cycling
> hardware would fix that, please educate me.

Glad you are back ... I think ... fully appreciating Rich Shepard
requires peculiar tastes :-)

My guess:

Your firewall/router and modem/switch probably have optional
settings that can block incoming ports (which you probably do not
use).  My further guess is that these settings are stored in EPROM,
and expanded into live code in faster RAM at device boot time. 
The code in RAM can be upset by static electricity, cosmic rays,
evil gremlins, and probable for this time of year, power glitches.

When a furnace motor or baseboard electric heater turns on,
either on your house load or in the other houses that you share
a transformer with, it can sag the power line, causing some
scrambled RAM in a simple device with a cheap power supply,
without necessarily triggering a reboot.  That could route the
SMTP port to the bit bucket.  A deep power cycle ( more than
10 seconds should be plenty ) will restore the modem/router
to status quo ante; a quick off/on may not clear the RAM or
trigger a full reset.

This is only a guess.  Before we moved, many of my computer
errors happened at the same time in the early morning, which
I tracked down to the scheduled turnon time for a neighbor's
furnace.  Electronics does the darnedest things.

Keith

P.S. The transfer from ROM to RAM is a common security hole in
many hardware designs.  With physical access to your device,
I can watch your secret passwords go by with a logic analyser
or a digitizing oscilloscope.  Do not use the same device 
passwords that you use for your bank accounts.

-- 
Keith Lofstrom          keithl at keithl.com



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