Wiki/mailserver/sieve.md

Sieve

Rule to automatically sort mails by alias

This Sieve rule filters mails by the mail alias they were sent to. Specifically, it uses a custom suffix separated by a dot: .([0-9a-zA-Z]*) It automatically creates a directory for that alias and moves the mail there. Then it stops processing.

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

if allof (header :regex "to" "^<name>.([0-9a-zA-Z]*)@<domain.tld>$")
{
        set :lower :upperfirst "target" "${1}";
        fileinto :create "${target}";
        stop;
}

Rule to change Subject of a mail on server

My alma mater introduced a change that subjects of all "external" mails are prefixed with [Extern]. I don't like that so I wrote a Sieve rule to remove it. The rule relies on some functions which need to be required.

require ["fileinto", "editheader", "variables", "regex"];

if allof (header :contains "subject" "[Extern]")
{
    # Match the subject w/o "[Extern]"
    if header :regex "Subject" "^\\[Extern\\] (.*)$" {
        # Delete header
        deleteheader "Subject";
        # Add stripped header again
        addheader :last "Subject" "${1}";
    }
}