[Dovecot] Questions about differences to other mail servers

[Kai Schaetzl]

Curtis Maloney wrote on Tue, 04 Apr 2006 09:16:07 +1000:

First, thanks for the quick answer!

> I remember this bug... I'm sure it was fixed.  Which version of the 
> ancient-but-venerable 0.99 are they shipping with CentOS? 

The rpm says 0.99.11. As you may know CentOS4 is based on RHEL4 and if you use it 
usally for the reason that you want to be able to get security patches and such for 
a longer time period than those meagre two years major distributions support their 
SOHO versions. Recompiling with each security patch is feasible if you have one or 
two machines, but not with more. So, I don't have a choice other than rely on rpms. 
I just checked and there's no 1.0 rpm on the dag repo which supplies a lot of 
updated rpms for the Red Hat bunch. Maybe that's because there's no official 1.0 
yet. I don't know. Usually, you will also not want to install a beta or RC on 
production machines.
So, what actually got  fixed in later versions do you think? It doesn't do the 
chdir for POP logins anymore? If so, I assume it also doesn't try to create the 
IMAP folder structure anymore as I reported down below?

> Check in the config file which users Dovecot is set to use.  It may be that you 
> need to chown the dir, or set Dovecot to use a different user.  NOTE: There's 
> more than one use setting in Dovecot, because of security and the auth daemon. 

I use PAM, so the only option is running it as root, per the documentation. So, 
this should not be a problem. I also see the dovecot processes appear after login 
under their uid in ps. (That's unique, I haven't yet seen another application that 
doesn't show the username but the uid.) I don't know or can't detect at which stage 
exactly it switches to that uid, but it seems to me that at authentication time it 
cannot traverse to its directories although a user belonging to that primary group 
(and the user is a member) should be able to do so. Could there be a connection to 
the uid thing? Maybe it then doesn't "grab" the gid of that user and acts 
"group-less"? (speculation, I don't know how this works on Linux.)

>  
> > 3. Furthermore, Dovecot created an IMAP directory structure within the 
> > home directory of most users like "mail/.imap/INBOX" (on some it reused 
> > the existing Mail -uppercase- directory). Just on a simple first POP3 
> > login. What's the reason for doing this? Maybe that user is never going to 
> > use IMAP? Does it test for both mail and Mail before it creates it's own 
> > structure or what does it do? I assume this is related to 
> > default_mail_env? 
>  
> Most likely, yes.  What do you have default_mail_env set to?  If you haven't set 
> it, Dovecot will try to auto-detect. 

Yeah, seems so and it's ok that way. The main reason for my question was why it did 
that. There's no need or use for an imap structure if that is a "simple" pop login. 
Is that related to the bug we where talking about above and also got fixed in the 
meantime?

>  
> > 4. Dovecot supports "auth plain", does it also support "auth login"? If 
> > so, how do I enable it? 
>  
> Does 0.99 support this?  Honestly, even though I still use 0.99, new installs 
> should be using the latest 1.0 release ( currently 1.0beta4)

Yes, I tried it by telnetting in to both uw-imap and dovecot. Dovecot 0.99 supports 
auth plain (only) and uw-imap supports auth login (only). Interesting mix ;-)
Do later dovecot builds support auth login? Unfortunately, there's no documentation 
on the wiki about the supported POP and IMAP commands.

Kai

-- 
Kai Schätzl, Berlin, Germany
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