Re: [Evolution] Errors receiving mail via POP

[Pete Biggs <pete biggs org uk>]

On Thu, 2014-09-11 at 02:16 +0200, Ángel González wrote:
> Patrick O'Callaghan wrote:
> > Any distributed system is subject to partial failure, i.e. one part
> > stops working or loses communication with another part. If data is in
> > the process of being moved between the two parts when that happens, the
> > designer has to decide between allowing data to be lost and opening the
> > possibility of duplicating it. Systems which aim for reliability
> > invariably choose the latter option, because the mess can always be
> > cleaned up later. Sometimes the cleanup is automatic (e.g. transactional
> > databases, many remote filesystems) and sometimes it's "manual" (i.e.
> > visible to the end user). AFAIK all email systems fall into the latter
> > category because a) it's not that big a deal, and b) doing it
> > automatically would be complicated and could introduce other errors.
> >
> > poc
>
> It's not hard to think on an IMAP server where the client is moving the
> emails using MOVE, the server is storing the files in maildir and thus
> it simply performs a rename() and the underlying filesystem is journaled
> (nothing fancy, just ext3 would do) and makes rename(2) atomic even in
> case of a server crash.

This is getting a bit off topic, but ...

I have a feeling that the "MOVE" IMAP command is relatively recent and
isn't supported by all servers and clients - it also breaks the "COPY"
and "MARK AS DELETED" that many people have been used to (to me that
gives me the warm fluffy feeling of making sure that mail is NEVER lost
by the server - paranoia helps when dealing with someone else's email!)

Also, the design of Maildir is such that all critical operations are
atomic - it's why the directories 'cur', 'new' and 'tmp' exist.

> Sometimes it's not hard to make things that work properly. But then
> nobody would notice :)

Nobody knows what a system manager does until they aren't there to do
it.

P.