Subject: Re: NNCP proxy for Internet mail providers?

From: John Goerzen <[email-masked]>
Date: Tue, 26 Oct 2021 21:39:39 -0500

On Tue, Oct 26 2021, John Goerzen wrote:

> On Tue, Oct 26 2021, [email-masked] wrote:
>
>> Would anyone be interested in a daemon or set of daemons that 
>> sat
>> between a "normal" IMAP4+SMTP-submission remote access mail 
>> host and a
>> local sendmail/nncp/postfix setup?  I figure this use case is 
>> what's
>
> That's a nice idea!
>
> So the idea is you have some Internet host -- maybe a cheap VPS 
> or something --
> that can download mail from the real provider, then gate it to 
> NNCP?
>
> I suspect you could make this work pretty easily with fetchmail 
> (particularly
> with the --bsmtp command, for instance).  My Exim example at
> http://www.nncpgo.org/Exim.html illustrates using bsmtp over 
> NNCP.  It could use
> --mda instead also.

You know, as the guy that wrote OfflineIMAP....

What would be REALLY cool would be a way to do an 
OfflineIMAP-style synchronization over NNCP.  That is, notice that 
certain changes have occurred on the local end, transmit commands 
via NNCP to cause those changes to occur on the IMAP server, and 
vice-versa.  As far as I know, there is nothing out there that can 
do that right now.  The closest you might come would be to use 
OfflineIMAP on a system with Internet connectivity, and then 
something like Syncthing to share a Maildir tree in an async 
fashion.  However, I'm not really sure how reliable that would be. 
It is entirely possible it would have significant drawbacks.

Syncthing and NNCP are interesting partners.  I wrote about a few 
of the possibilities at 
https://changelog.complete.org/archives/10219-a-simple-delay-tolerant-offline-capable-mesh-network-with-syncthing-optional-nncp

- John