dovecot - Sep 2013 - Courier migration and vpopmail with dovecot-lda

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.

Thanks,

Charles
-- 
Charles Sprickman
NetEng/SysAdmin
Bway.net - New York's Best Internet www.bway.net
spork at bway.net - 212.982.9800

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