Dovecot's Sieve filter creates duplicate of incoming email

Question

I'm using Dovecot with Sieve filters.

I've got a default filter: sieve_before = /var/lib/dovecot/sieve.d/default.sieve

And after that some user's filter: sieve_dir = ~/sieve

Problem: Dovecot filters "default.sieve" with original incoming message but user's filter filters with duplicate of message. So if I want to move incoming message to another folder - it works but original of the message stays in INBOX. Solution is simply I believe but I can't figure it out.

User's filter contains:

fileinto "Folder";

Log:

...: stored mail into mailbox 'INBOX'
...: stored mail into mailbox 'Folder'

if duplicate is false

Here is the content of sieve_before filter:

require ["fileinto", "imap4flags"];
if header :contains "X-Spam-Flag" "YES" {
setflag "\\Seen";
fileinto "Spam";
stop;
}

Answer 1

Solved.

Change this:

require ["fileinto", "imap4flags"];
if header :contains "From" "something" {
    fileinto "Folder";
    addflag "\\Seen";
stop;
}

By this:

require ["fileinto", "imap4flags"];
if header :contains "From" "something" {
    fileinto "Folder";
    stop;
}