[SLUG] POP3 and IMAP

[Paul Teasdale]

On Thursday 20 Apr 2006 19:14, Mike Bennett wrote:
> On 4/20/06, David Webster <dave at dave-webster.com> wrote:
> > I did some reading around and found that there is a third way.  IMAP
>
> Aha. Of course. Didn't think of IMAP because I've very very rarely
> seen it in use.
> Of course, you do have to have a mailserver that supports ~IMAP (which
> most ISPs probably don't).
>
I had exactly the same problem as David a few years ago now and so decided to 
look at IMAP and it works fantastically well. This is how I setup it up.

I currently have three ISP POP accounts at home. None of these ISPs support 
IMAP. What I did was to setup my own mail server using Fetchmail, Exim and 
Dovecot (a POP3/IMAP server combined). 

Fetchmail basically collects the mail from each of my ISP POP accounts and 
deletes anything sucessfully fetched. It then "throws" the mail it fetches at 
Exim.

Exim examines where the mail is going (after Spamassassin and Clam-AntiVirus 
have had their turn to snaffle it) and delivers it to the correct user's 
spool file. It does this because I have configured it to handle my 3 e-mail 
domains as local domains. BTW Exim is also responsible for sending outbound 
e-mail that we wish to send also.

Finally the user comes along with their IMAP compliant e-mail client to look 
at their mail. It does this by contacting the Dovecot server which then 
collects all the mail from the users spool file, deletes it and then puts the 
mail into the inbox of the IMAP folder structure (unless they have set up 
some filters in their e-mail client to deliver it elsewhere). I have stored 
this folder structure for each user in $HOME/Mail (with Dovecot it's 
configurable as is the choice of whether you want to use Maildir or Mbox 
formats). Each user (read my wife and I) can build the folder structure up as 
we wish using our chosen client.

It works very well because all our mail is held in one set of folders 
regardless of where you view it from. I mainly use KMail and my Mrs uses 
Thunderbird. I also use SquirrelMail (which is a webmail package written in 
PHP that's compatible most SMTP and IMAP servers) to access my e-mail from 
work and when I am on business via a web browser. I run SquirrelMail using 
Apache2 via HTTPS to make it more difficult for someone to grab our passwords 
as they are encrypted. I have also set it up to redirect to HTTPS if I 
accidentally type HTTP. Because I have signed my own SSL certificate I get a 
warning in each new browser I use stating that the certificate is signed by 
an unrecognised authority. I'm not worried about it's authenticity (I know my 
own server) so long as it encrypting the information (especially our 
passwords).

I have also set up the same scenario for the company I work for except I used 
Fetchmail, Sendmail and UW-IMAP because these were the default Slackware 
packages which I understood better at the time I set the system up. If I got 
the chance to do it again I would use Debian, Fetchmail, Exim and Dovecot 
because they are either easier to configure (Exim) or more powerful 
(Dovecot). I would use Debian because the packages are very well "laid out" 
and act as a good starting point to build an advanced configuration from.

I have only found one small problem. I have to run my PC 24/7 which personally 
I don't mind but it's not very green. At one point I bought a Linksys NSLU2  
with the hopes of customising its firmware (http://www.nslu2-linux.org) and 
then running it as an e-mail server. These are a small (Windows only if your 
believe Linksys) NAS devices but are actually embedded Linux inside. They 
have an Intel XScale processor and 32Mb of memory and use a fraction of 
electric as compared with a PC. Unfortunately it just wasn't powerful enough 
to handle all the servers, spam and virus checking etc. 

I would be willing to attempt a meeting and do a talk on these e-mail related 
servers at some point if anyones interested. I could also bring along the 
Linksys device for people to take a look at if interested as it is still 
customised and can be logged into via HTTP (the normal Linksys way) or SSH 
(due to its nslu2-linux firmware).

Regards,
Paul.
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