This documentation is for Dovecot v2.x, see wiki1 for v1.x documentation.

Pigeonhole Sieve examples

Below are some simple Sieve code examples, more can be found from http://libsieve.sourceforge.net/script1.php and http://fastmail.wikia.com/wiki/SieveExamples.

Mail filtering by various headers

Use if/elsif/else to store messages into various folders/subfolders:

Forward mails with "order" or "buy" in their subject to another address:

Message-ID and recipient of forwarded message are stored in a .dovecot.lda-dupes at users home directory to prevent mail loops.

Flagging or Highlighting your mail

Some mail readers use these flags:

require "imap4flags";
require "regex";
if anyof (exists "X-Cron-Env",
          header :regex    ["subject"] [".* security run output",
                                        ".* monthly run output",
                                        ".* daily run output",
                                        ".* weekly run output"]) {
  addflag "$label1"; # ie 'Important'/red label within Thunderbird

# Other flags:
# addflag "$label1";  # Important: #ff0000 => red
# addflag "$label2";  # Work:      #ff9900 => orange
# addflag "$label3";  # personal:  #009900 => green
# addflag "$label4";  # todo:      #3333ff => blue
# addflag "$label5";  # later:     #993399 => violet
#
}

Local copy of your emails:

require ["envelope", "imap4flags"];
if envelope "from" "my_address@my_domain.com"
{
   setflag "\\seen";
}

Useful, when you want sieve to manage your incoming and outgoing email (you must ask your mail reader to Bcc your mail to your dovecot in this case).

Spam/Virus rules

Most spam and virus scanners add a special header to mail messages, so that users can apply filtering accordingly. Depending on how the Sieve interpreter is configured, filtering can either be performed by evaluating these headers directly, or using the spamtest and virustest extensions.

Direct filtering using message header

Evaluating the headers directly is always possible as long as the headers are actually added to the messages by the scanner software. For example, to file SpamAssassin-tagged mails into a folder called "Spam":

require "fileinto";
if header :contains "X-Spam-Flag" "YES" {
  fileinto "Spam";
}

The following example discards SpamAssassin-tagged mails with level higher than or equal to 10:

if header :contains "X-Spam-Level" "**********" {
  discard;
  stop;
}

Some spam scanners only produce a numeric score in a header. Then, the test becomes more involved:

require ["comparator-i;ascii-numeric","relational"];
if allof (
   not header :matches "x-spam-score" "-*",
   header :value "ge" :comparator "i;ascii-numeric" "x-spam-score" "10" )
{
  discard;
  stop;
}

NOTE: Be very careful when matching against spam score headers using the relational extension and the i;ascii-numeric comparator. This comparator can only be used to match unsigned integers. Strings that do not begin with a digit character represent positive infinity and will therefore always be larger than any score mentioned in your rule! That is why the above example first checks the minus sign explicitly.

Filtering using the spamtest and virustest extensions

When the spamtest and virustest extensions are configured on the server (here is explained how), users (and GUIs) can have a much easier way to filter spam and virus messages respectively. To filter spam, the spamtest extension can for example be used as follows:

require "spamtestplus";
require "fileinto";
require "relational";
require "comparator-i;ascii-numeric";

/* If the spamtest fails for some reason, e.g. spam header is missing, file
 * file it in a special folder.
 */
if spamtest :value "eq" :comparator "i;ascii-numeric" "0" {
  fileinto "Unclassified";

/* If the spamtest score (in the range 1-10) is larger than or equal to 3,
 * file it into the spam folder:
 */
} elsif spamtest :value "ge" :comparator "i;ascii-numeric" "3" {
  fileinto "Spam";

/* For more fine-grained score evaluation, the :percent tag can be used. The
 * following rule discards all messages with a percent score
 * (relative to maximum) of more than 85 %:
 */
} elsif spamtest :value "gt" :comparator "i;ascii-numeric" :percent "85" {
  discard;
}

/* Other messages get filed into INBOX */

The virustest extension can be used in a similar manner:

require "virustest";
require "fileinto";
require "relational";
require "comparator-i;ascii-numeric";

/* Not scanned ? */
if virustest :value "eq" :comparator "i;ascii-numeric" "0" {
  fileinto "Unscanned";

/* Infected with high probability (value range in 1-5) */
} if virustest :value "eq" :comparator "i;ascii-numeric" "4" {
  /* Quarantine it in special folder (still somewhat dangerous) */
  fileinto "Quarantine";

/* Definitely infected */
} elsif virustest :value "eq" :comparator "i;ascii-numeric" "5" {
  /* Just get rid of it */
  discard;
}

Plus Addressed mail filtering

Using the subaddress extension, it is possible to match against the 'detail' part of an e-mail address, e.g. a '+tag' suffix to the local part of the address. This is for example useful when you don't want just any +tag to create a directory, but you want to use tagged addresses such as with amavisd-new. This example would place email addressed to user+spam@example.com into user's Spam folder.

require ["fileinto", "envelope", "subaddress"];
if envelope :detail "to" "spam"{
  fileinto "Spam";
}

The following more advanced example uses the subaddress extension to handle recipient addresses structured as sales+<name>@company.com in a special way. The <name> part is extracted from the address using variables extension, transformed into a format with the first letter in upper case and subsequently used to create the folder name where the message is stored. The folder name is structured as users/<name>. If the +<name> detail is omitted from the recipient address, the message is filed in the sales folder.

require ["variables", "envelope", "fileinto", "subaddress"];

if envelope :is :user "to" "sales" {
  if envelope :matches :detail "to" "*" {
    /* Save name in ${name} in all lowercase except for the first letter.
     * Joe, joe, jOe thus all become 'Joe'.
     */
    set :lower :upperfirst "name" "${1}";
  }

  if string :is "${name}" "" {
    /* Default case if no detail is specified */
    fileinto "sales";
  } else {
    /* For sales+joe@ this will become users/Joe */
    fileinto "users/${name}";
  }
}

To work with Postfix, this requires that the envelope "to" still contains the full address, so pass it with the -a flag.

dovecot unix    -       n       n       -       -      pipe
  flags=DRhu user=mail:mail argv=/usr/local/libexec/dovecot/dovecot-lda
  -f ${sender} -d ${user}@${nexthop} -a ${recipient}

or

mailbox_command = /usr/lib/dovecot/dovecot-lda -a "$RECIPIENT"

Vacation auto-reply

Auto-responder functionality is implemented using the vacation extension. The following script sends out-of-office replies when the message is not spam:

require ["fileinto", "vacation"];
# Move spam to spam folder
if header :contains "X-Spam-Flag" "YES" {
  fileinto "spam";
  # Stop here so that we do not reply on spams
  stop;
}
vacation
  # Reply at most once a day to a same sender
  :days 1
  :subject "Out of office reply"
  # List of additional recipient addresses which are included in the auto replying.
  # If a mail's recipient is not the envelope recipient and it's not on this list,
  # no vacation reply is sent for it.
  :addresses ["j.doe@company.dom", "john.doe@company.dom"]
"I'm out of office, please contact Joan Doe instead.
Best regards
John Doe";

It's also possible to include the original subject using the variables extension:

require ["variables", "vacation"];
# Store old Subject line so it can be used in vacation message
if header :matches "Subject" "*" {
        set "subjwas" ": ${1}";
}
vacation
  :days 1
  :subject "Out of office reply${subjwas}"
  :addresses ["j.doe@company.dom", "john.doe@company.dom"]
"I'm out of office, please contact Joan Doe instead.
Best regards
John Doe";

Include scripts

It's possible to include other Sieve scripts in your script:

require ["include"];
include :global "global-spam";
include :personal "my-own-spam";

The lookup directories can be specified with:

plugin {
  # Directory for :personal include scripts. The default is to use home directory.
  sieve_dir = %h/sieve

  # Directory for :global include scripts (not to be confused with sieve_global_path).
  # If unset, the include fails.
  sieve_global_dir = /etc/dovecot/sieve/
}

Both sieve_dir and sieve_global_dir may also be overridden by userdb extra fields.

It's not currently possible to use subdirectories for the scripts. Having a '/' character in the script name always fails the include. This is just an extra check to avoid potential problems with including scripts within mail directories.

Archiving a Mailinglist by Date

You can archive messages from mailing lists in a date-structured folder tree as follows:

require ["variables","date","fileinto","mailbox"];

# Extract date info
if currentdate :matches "year" "*" { set "year" "${1}"; }
if currentdate :matches "month" "*" { set "month" "${1}"; }

# Archive Dovecot mailing list items by year and month.
# Create folder when it does not exist.
if header :is "list-id" "dovecot.dovecot.org" {
  fileinto :create "INBOX.Lists.${year}.${month}.dovecot";
}

For example, in March 2013 this puts messages from the Dovecot mailing list in a folder called INBOX.Lists.2013.03.dovecot. It combines the date and variables extensions to extract the required date strings. Using the :create argument for the fileinto command, the indicated folder is created automatically if it doesn't exist. The :create argument is provided by the mailbox extension.

Translation from Procmail

There exists a script which attempts to translate simple Procmail rules into Sieve rules: http://www.earth.ox.ac.uk/~steve/sieve/procmail2sieve.pl (dovecot.org mirror)

Here's the original post announcing it: http://dovecot.org/list/dovecot/2007-March/020895.html

Pigeonhole/Sieve/Examples (last edited 2013-08-24 00:55:39 by PascalVolk)