I changed my mind. In 1bf8f1991f I allowed Unicode domain names to go into the database. I thought that was nice because it's what the user *means*. But it's not how the web works. Web and DNS were working, but mail wasn't. Postfix (as shipped with Ubuntu 14.04 without support for SMTPUTF8) exists in an ASCII-only world. When it goes to the users/aliases table, it queries in ASCII (IDNA) only and had no hope of delivering mail if the domain was in full Unicode in the database. I was thinking ahead to SMTPUTF8, where we *could* put Unicode in the database (though that would prevent IDNA-encoded addressing from being deliverable) not realizing it isn't well supported yet anyway.
It's IDNA that goes on the wire in most places anyway (SMTP without SMTPUTF8 (and therefore how Postfix queries our users/aliases tables), DNS zone files, nginx config, CSR 'CN' field, X509 Common Name and Subject Alternative Names fields), so we should really be talking in terms of IDNA (i.e. ASCII).
This partially reverts commit 1bf8f1991f, where I added a lot of Unicode=>IDNA conversions when writing configuration files. Instead I'm doing Unicode=>IDNA before email addresses get into the users/aliases table. Now we assume the database uses IDNA-encoded ASCII domain names. When adding/removing aliases, addresses are converted to ASCII (w/ IDNA). User accounts must be ASCII-only anyway because of Dovecot's auth limitations, so we don't do any IDNA conversion (don't want to change the user's login info behind their back!). The aliases control panel page converts domains back to Unicode for display to be nice. The status checks converts the domains to Unicode just for the output headings.
A migration is added to convert existing aliases with Unicode domains into IDNA. Any custom DNS or web settings with Unicode may need to be changed.
Future support for SMTPUTF8 will probably need to add columns in the users/aliases table so that it lists both IDNA and Unicode forms.
CHANGELOG
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v0.08 (April 1, 2015)
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Mail:
* The Roundcube vacation_sieve plugin by @arodier is now installed to make it easier to set vacation auto-reply messages from within Roundcube.
* Authentication-Results headers for DMARC, added in v0.07, were mistakenly added for outbound mail --- that's now removed.
* The Trash folder is now created automatically for new mail accounts, addressing a Roundcube error.
DNS:
* Custom DNS TXT records were not always working and they can now override the default SPF, DKIM, and DMARC records.
System:
* ownCloud updated to version 8.0.2.
* Brute-force SSH and IMAP login attempts are now prevented by properly configuring fail2ban.
* Status checks are run each night and any changes from night to night are emailed to the box administrator (the first user account).
Control panel:
* The new check that system services are running mistakenly checked that the Dovecot Managesieve service is publicly accessible. Although the service binds to the public network interface we don't open the port in ufw. On some machines it seems that ufw blocks the connection from the status checks (which seems correct) and on some machines (mine) it doesn't, which is why I didn't notice the problem.
* The current backup chain will now try to predict how many days until it is deleted (always at least 3 days after the next full backup).
* The list of aliases that forward to a user are removed from the Mail Users page because when there are many alises it is slow and times-out.
* Some status check errors are turned into warnings, especially those that might not apply if External DNS is used.
* For non-ASCII domain names, we will keep the Unicode encoding in our users/aliases table. This is nice for the user and also simplifies things like sorting domain names (using Unicode lexicographic order is good, using ASCII lexicogrpahic order on IDNA is confusing).
* Write nsd config, nsd zone files, nginx config, and SSL CSRs with domains in IDNA-encoded ASCII.
* When checking SSL certificates, treat the CN and SANs as IDNA.
* Since Chrome has an interesting feature of converting Unicode to IDNA in <input type="email"> form fields, we'll also forcibly convert IDNA to Unicode in the domain part of email addresses before saving email addresses in the users/aliases tables so that the table is normalized to Unicode.
* Don't allow non-ASCII characters in user account email addresses. Dovecot gets confused when querying the Sqlite database (which we observed even for non-word ASCII characters too, so it may not be related to the character encoding).
Joshua Tauberer