[Dovecot] Courier migration and vpopmail with dovecot-lda

[Anton Lundin]

On 18 September, 2013 - Charles Sprickman wrote:

> I've been using Dovecot in some fresh installs lately and have found
> it fairly easy to configure.  However I'm starting on a migration
> that involves moving from some very old software (ancient vpopmail,
> qmail and Courier).
> 
> On the Courier front, I've reviewed the migration page in the wiki,
> and it looks like the main concerns are just matching the namespace
> and then using the migration script to create new subscription and
> uidlist files.  Given that my Courier IMAP setup is so old (4.0.6),
> is there anything to be aware of that's not covered in the wiki due
> to the age of Courier here?
> 
> Are there any other general issues to be aware of as far as
> interactions with MUAs are concerned?  For example, if Courier has
> been presenting the user's MUA with a given set of IMAP capabilities
> and then the MUA sees a bunch of extra capabilities on a subsequent
> login, will that trigger any strange behavior?
> 
> And lastly on this subject, I will obviously be doing some testing
> before cutting over to the other server.  Is it valid in something
> like Thunderbird to have it pointed to "imap.domain.com" and then
> change the imap server to point to something like
> "testimap.domain.com" for testing whether subscriptions and the
> uidlists are working as expected or should I fully replicate the
> move as an end user would see it by making the change in my local
> hosts file?
> 
> Now, assuming that portion of the move goes alright, I'm incredibly
> confused about getting Dovecot and Vpopmail working together.  I
> assume that initially I can stick with the Maildir++ mailbox format
> and let vpopmail's vdelivermail continue working as my LDA -
> vdelivermail understands how to find the user's Maildir, it can
> check quotas, and it can update the maildirsize file (which I'm
> assuming dovecot can also read and then report quota/usage to an
> IMAP client).  However it does look like the Dovecot-only mailbox
> format(s) will offer much better performance than Maildir as the two
> dbox formats are the only supported mailbox formats with separate
> index files, correct?  Is there any guidance on how to use dovecot's
> LDA with a virtual mail system such as vpopmail?  From what I've
> read so far, I probably don't want to use the vpopmail extension
> supplied with dovecot, but query the mysql vpopmail db directly.
> I'm finding a ton of info while searching for this, but most deals
> with older versions of dovecot, and there are also many "this works
> but I don't know why" tutorials on combining dovecot and vpopmail
> and dovecot's own LDA.  I'm not even able to guess how one handles
> the per-user .qmail files in vpopmail if not using vdelivermail
> (this is where we enable/disable spam filtering by piping the
> message through spamc).
> 
> Any input on the overall migration process is appreciated.  It's a
> bit overwhelming as I have to deal with a big jump in the vpopmail
> version, rebuilding qmail with a ridiculous number of patches, and
> then on top of that a migration to new imap/pop server software.
> eek.

Hi Charles!

I can share some of my war-stories about qmail/vpopmail.

Along time ago i ran quite a few qmail/vpopmail/courier/ezmlm/qmailadmin
clusters and back then i thought it was the only rely good way of
running it. Then the years passed and when i needed to add patches to
qmail consisting of more code than qmail started out with it got quite
frustrated.
Due to speed and scalability we didn't run with a db-backend for
vpopmail, we used vpasswd/cdb(?) hash-files and that ran quite well.

So when it was time to migrate i came up with the following solution:

I ran postfix as smtp-server, querying vpopmail via a tcp:-maps to a daemon
written in perl, that ran diffrent vpopmail-commands.
That old daemon is now available at:
https://github.com/glance-/postfixvpopmail/

For some reason that i can't really remember vdelivermail was just
incapable of being used in this case to deliver mail, i think it had
something to do with .qmail-files and might have bin something with
ezmlm, so i used qmail as a lda, and had postfix pipe mail to
qmail-inject.
This way we kept qmailadmin/ezmlm running as they did before and just
replaced the world-facing components.

On top of that i ran Dovecot with the vpopmail plugin. This was a realy
old dovecot, probaby like 1.0.x or something, but everything worked
smoothly. I just followed the notes on the wiki about uidl-format and
no users noticed.


I actually just checked, and that server is still running strong, and
handling mail for a couple of k users, so it couldn't bin that bad
design =)
Btw. Its still running Debian Sarge =)


I hope you might have gotten some ideas about what to do with a old
qmail/vpopmail install.


//Anton


-- 
Anton Lundin	+46702-161604