BigSmoke » zimbra

Disable Zimbra’s duplicate mail detection

halfgaar — Mon, 18 Jan 2010 11:14:09 +0000

Zimbra can discard duplicates of incoming mail. This has certain advantages, but for us, where different people use the same account with different identities, this prevents a message from being delivered to multiple virtual inboxes.

To disable this, do:

zmprov mcf zimbraMessageIdDedupeCacheSize 0
zmmailboxdctl restart

Unfortunately, this has the annoying problem that conversations aren’t detected for duplicates of a message. See this forum thread for more info.

Lowering Bayes score for Zimbra’s Spamassassin config

halfgaar — Mon, 18 Jan 2010 00:25:54 +0000

The Spamassassin config in Zimbra has a very high default score for bayes matching of 99, 95, 90, etc, percent. A mail with subject and body “test” or “asdfaewf a” is often marked as 99% bayes, even though the spamfilter has seen no training mail. This is absurd.

To amend this, I put this in /opt/zimbra/conf/spamassassin/local.cf:

score BAYES_99 2.500
score BAYES_95 2.000
score BAYES_90 1.500
score BAYES_85 1.000
score BAYES_80 0.500

Configuring fetchmail to deliver to Zimbra with custom header added

halfgaar — Sun, 17 Jan 2010 18:36:56 +0000

I needed to fetch mail from a POP3 account and deliver it to a Zimbra account. Because I’m doing this for multiple POP3 accounts, I want to add a header which I can use in Zimbra to filter. This is what we made:

poll server user "user" pass "secret" mda "formail -A 'X-Zimbra-To: user@domain.org'| /opt/zimbra/postfix/sbin/sendmail -i -t service@sicirec.org"

The -i tells sendmail to ignore a single dot on a line, because that would normally mean end of mail. The -t is “to” (not the header “To:“).

It is a bit unclear why postfix delivers locally to Zimbra, since doing mail user@ourdomain.org routes through an external SMTP server, which is configured in Zimbra to be used as MTA for outgoing mail. It is configured as ‘webmail MTA’.

Fixing spamassassin rule in Zimbra

halfgaar — Sun, 17 Jan 2010 18:15:17 +0000

Spamassassin has had a bug for a while, marking any mail from 2010 and later as spam because it’s from “far into the future”. This was very crudely done as this regexp: /20[1-9][0-9]/. Because of that, almost all mail from 2010 onward is marked as spam.

I Changed the regex to match for 2020 or later, but that’s not really a fix. Even the spamassassin maintainers ‘fixed’ it that way.

What I have to look out for though, is that this file may get overwritten when I upgrade zimbra. sa-update doesn’t seem to work on zimbra, so I don’t really know what the best way of getting new rules is.

Set proper origin domain for Zimbra server

halfgaar — Tue, 12 Jan 2010 14:24:14 +0000

I have a zimbra server fooled into thinking it hosts a particular domain. Part of the fooling involves setting a different SMTP server than localhost for all outgoing mail. Luckily, Zimbra can do that.

The downside of that is that when you send mail to “root”, the other SMTP server qualifies it with its domain and the mail appears to be coming from the wrong server.

To fix it, specify this in the /opt/zimbra/postfix/conf/main.cf:

myorigin = example.com

This seems to work without caveats. However, I don’t know if zimbra overwrites this config file at some point.

As always, pick a domain that exists, otherwise a lot of mailservers won’t accept it. You don’t even need an MX record, A or CNAME if enough.

Disabling Zimbra’s spam learning

halfgaar — Mon, 21 Dec 2009 13:03:02 +0000

Zimbra learns ham and spam by sending it to certain mailboxes. For our setup, this doesn’t work (easily), because our server is configured to always send mail to another SMTP server and not do any local delivery. I did that, because our zimbra server is not actually on the domain it thinks.

To disable the learning accounts, I did this:

zmprov mcf zimbraSpamIsSpamAccount ''
zmprov mcf zimbraSpamIsNotSpamAccount ''
zmcontrol stop
zmcontrol start

I didn’t delete the accounts, so I can enable it later.

To enable it, I guess I have to configure these two accounts on our hosting provider’s servers, fetch and deliver them to Zimbra and it works. I’ll do that some time…

LDAP search filter for Thunderbird and Zimbra

halfgaar — Thu, 10 Dec 2009 19:17:14 +0000

When configuring an LDAP addressbook, one thing that has given me a lot of trouble, is the LDAP filter. Here are two I use.

For thunderbird:

(|(cn=%v*)(mail=%v*)(sn=%v*)(displayName=%v*)(givenName=%v*))

For Zimbra:

(|(cn=%s*)(mail=%s*)(sn=%s*)(displayName=%s*)(givenName=%s*))

In Zimbra, I had to configure our ruby-ldapserver to never return more than 50 results, because in the configuration panel, it runs a test based on a search query, but also with the %s literally repeated. This causes the SQL query that is generated to be %s% and that gives a whole lot of results, hanging Zimbra. It is beyond me why Zimbra runs this second query, but I guess it’s a bug.