i read the link.
protocol lda {
    mail_plugins = ... acl
}

protocol imap {
    mail_plugins = ... acl imap_acl
}
those settings were set . I had added them in dovecot.conf.

Also i had added;
# mysql -uroot -p
mysql> USE vmail;
mysql> SELECT * FROM share_folder;
+-----------------+--------------------+-------+
| from_user       | to_user            | dummy |
+-----------------+--------------------+-------+
| from@domain.ltd | testing@domain.ltd | 1     |
+-----------------+--------------------+-------+

but when i add a shared file called vfile into my main account via imap, i can't see second account it.
what can the problem?

i followed the link i get an error via the telnet section;

# telnet 127.0.0.1 143
Trying 127.0.0.1...
Connected to 127.0.0.1.
Escape character is '^]'.
* OK [CAPABILITY IMAP4rev1 LITERAL+ SASL-IR LOGIN-REFERRALS ID ENABLE IDLE STARTTLS AUTH=PLAIN AUTH=LOGIN] Dovecot ready.
login from@test.org 111
login BAD First parameter in line is IMAP's command tag, not the command name. Add that before the command, like: a login user pass