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@bway.net - 212.982.9800