[Freedombox-discuss] Email on the FreedomBox Discussion

[John Gilmore]

> I see an availability issue running an e-mail server in FB,
> Normal users doesn't own what we can call a reliable environment. There are 
> blackouts from time to time, the hair drier can shut down power, my ISP 
> connection is not redundant, etc. For other services like instant messaging or 
> VoIP if my environment fail I'm not able to access my network from my client 
> devices (unless I'm on the road) and I will be unavailable to others anyway. 

I've been running web and mail servers out of my home for decades.
Power blackouts are infrequent here (in San Francisco), but if you
care, the vast majority of them can be handled with a small UPS
(uninterruptable power supply).

Even here in earthquake country, I've had more downtime from software
problems and system administration, than I have had from power
problems and ISP unreliability.

A small UPS can power your DSL gateway, your DreamPlug, and a small
ethernet switch for many, many hours.  However, the only way to find
out whether your whole Internet connection will actually operate
through a power outage is to have a power outage and try it.  We
discovered a few years ago, when a big PG&E transformer blew up, that
my line ran through a Pac Bell "channel bank" that had no backup
power.  So even though my end of it was backed-up with a UPS, and so
was my ISP's, our telco had screwed us.  (They fixed it, we think.)

PS: Put your server -- and your freezer and your smoke alarms --
on a different circuit than your hair dryer.

> But mail is different, mail is asynchronous, if the FB is not available when 
> the message reach my home, it will be returned back to the sender and that's 
> something we don't want to see.

This is false.  SMTP mail is queued by the sender and retried later.  If 
a LONG outage occurs (more than 24 hours), some will bounce, but that's
good -- it notifies your correspondents that you aren't getting their
messages.

Indeed, some foolish anti-spam systems work by rejecting every message
the first time they receive it, with a "temporary problem, retry
later" error code.  Their theory is that REAL mail will get retried later
but spam-sending software won't bother retrying.  (This is foolish
because it delays all valid mail -- and it assumes spammers can't use
queueing software.)

> I think it's needed to provide some availability enhancement to FB users. 
> Something like an equivalent to the MX priority DNS entries where if the FB 
> fails, mails are forwarded to a backup server and resent to the FB as it 
> becomes available. Obviously, users should be able to choose whether they want 
> to use this backup server or not.

Existing mail protocols and software already have MX support.  Little
or no change is needed to support backup mail servers that queue the
messages and forward them to the primary server when it comes back up.

All it should take is for you to set your MX records, and make an
arrangement with your backup mail provider.  They'd need to configure
their mail software so it knows that incoming mail for <you at yourdomain>
shouldn't be rejected with "We aren't <yourdomain>" but should be
dropped into the queue.

Your backup mail provider can be a friend with a FreedomBox -- or
anybody else who runs a mail server, including a giant faceless
corporation in a data center.

Of course, your mail is going to be sitting on your backup provider's
mail queue in plaintext -- so be sure you trust your backup provider.

	John