Sieve mail filtering language is an application created in 2008. Sieve is a programming language that can be used for email filtering. It owes its creation to the CMU Cyrus Project, creators of Cyrus IMAP server. The language is not tied to any particular operating system or mail architecture. Read more on Wikipedia...

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Example code from Wikipedia:

# Sieve filter

# Declare the extensions used by this script.
require ["fileinto", "reject"];

# Messages bigger than 100K will be rejected with an error message
if size :over 100K {
   reject "I'm sorry, I do not accept mail over 100kb in size. 
Please upload larger files to a server and send me a link.

# Mails from a mailing list will be put into the folder "mailinglist" 
elsif address :is ["From", "To"] "mailinglist@blafasel.invalid" {
   fileinto "INBOX.mailinglist";

# Spam Rule: Message does not contain my address in To, CC or Bcc
# header, or subject is something with "money" or "Viagra".
elsif anyof (not address :all :contains ["To", "Cc", "Bcc"] "me@blafasel.invalid", 
header :matches "Subject" ["*money*","*Viagra*"]) {
      fileinto "INBOX.spam";

# Keep the rest.
# This is not necessary because there is a "implicit keep" Rule
else {

Last updated August 9th, 2020

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