On Thu, 14 Sep 2017 07:38:57 -0400
rhkra...@gmail.com wrote:

> On Thursday, September 14, 2017 03:56:38 AM to...@tuxteam.de wrote:
> > On Wed, Sep 13, 2017 at 03:32:33PM -0400, Steve Kleene wrote:  
> > > My employer is forcing me to shut down my long-time Linux mail
> > > server.  I have no choice in the matter.
> > > 
> > > My employer uses Microsoft Exchange/Outlook for mail.  They have
> > > an Outlook Web App (OWA) that I can access from Firefox, but as
> > > far as I can tell you cannot save a file to the local disk with
> > > OWA.  That makes OWA pretty useless.  The documentation, if it
> > > can be believed, says that I can access Outlook with POP3 and
> > > IMAP4 programs including Thunderbird.  
> > 
> > As others have said, IMAP is the best path (if the Exchannge server
> > is set up for it).  
> 
> I'm sort of moving OT, but want to ask: presumably you think IMAP is 
> preferable to POP3--what makes you say that (in general)?
> 
> It's been a long time since i chose to use pop3 instead of imap--in
> fact, iirc, imap became an option later, and my decision was more
> whether to stick with pop3 or switch to imap.
> 
> I prefer pop3 because it (in most cases, unless set otherwise or
> dealing with gmail) deletes the email from the email server, which is
> what I prefer.
> 
> I presume imap gives you an option to delete mail from the server?
Yes, there's quite an extensive IMAP protocol, allowing various
processing, including multiple directories on the server. It keeps
flags for 'seen', 'read' and 'deleted' (removing an email completely is
'purging') and can synchronise one or all directories with a client's
cache. It can send as well as receive email, though SMTP is normally
still used.
> 
> I recognize that leaving email on the server can make it easier to
> access your email from multiple devices, but (1) I rarely have that
> need (maybe not in the last 10 years), and (2), when I do, I can set
> pop3 to leave email on the server (but, iirc, I typically set my
> "main" email device to delete it from the server--iirc, if I didn't,
> I'd keep getting the same emails sent to me over and over--but maybe
> I'm not remembering that correctly.
> 

That's a matter for the client/downloader rather than the server. POP3
is a simple 'empty the mailbox' protocol, and doesn't bother keeping
records of message IDs, or indeed anything else. The POP3 downloader in
Small Business Server 2003 would download 'kept' mail multiple times,
the downloader in SBS2008 did not. It's up to the downloader to check
waiting message IDs against already stored message IDs, to decide
whether to download the whole message (again).

You've pretty much answered your own question: it's horses for courses,
IMAP is the only possibility if you work server-based, keeping all
email centrally with, at most, caches on the client machine(s). POP3 is
simplest if you use only the one email client, and that client can deal
with stored email in the way you need, with locally-defined directories
to organise things. You need to organise your own POP3 email backup,
generally a server providing IMAP will itself be routinely backed up,
and most people also keep local caches.

Microsoft's protocol for Exchange and Outlook is MAPI, generally
unpublished and of increasing complexity. It was originally the MS
'embrace and extend' strategy for displacing IMAP and taking ownership
of all server-based email, but that didn't quite happen, and Exchange
servers still offer access to the standard protocols. It still has extra
features such as calendars, linkage with customer databases and
'proper' external email client access through a webserver, in addition
to basic webmail.

-- 
Joe

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