[Dovecot] Problem with dovecot-lda

[Wolfgang Ganzert]

Hello Ladies and Gentlemen,

first of all I have to say that dovecot is really impressive. I seems to be a 
very goot IMAP server and has in general a good documentation.

I'm a beginner regarding the administration so please excuse if my questions 
sound silly but I want to learn to administrate these sophisticated things.

Now here's my configuration:
Linux openSuSE 12.1
Postfix 2.8.8
Dovecot 2.0.16

Boundary condition:
Postfix as smtp (Postfix is configured as relay server; mail is sent to 
smtp.web.de if mail is not locally distributed)
Dovecot  as IMAP server in my private network (192.168....)

Situation:
I want to store outgoing mail which is send by postfix also in a "SENT" folder 
in Dovecot. The SENT folder is available and created through the plugin 
"autocreate". The main.cf file from postfix contains the following mailbox 
command:

mailbox_command = /usr/lib/dovecot/dovecot-lda -f "$SENDER" -a "$RECIPIENT" -m 
SENT

If I send a simple mail from the shell with the following command

echo "Hello me" | mail -s "Dovecot test 50, shell nach SENT" $USER

the mail is send to my mailbox and stored in the folder "SENT" as unread.

Problem:
1.
I would expect to have to mails coming in; one in my "SENT" folder because 
this is copy of the mail and another one which is the incoming folder because 
the mail was sent to me. But, there is no mail in the incoming folder.
2.
If I use a mail client like kmail2 the same thing happens. The mail is 
distributed to the SENT folder but there's no copy in the incoming folder.
3.
If I send a mail to my adress at @web.de with the postfix configuration from 
above I do not receive the mail at web.de. 
4.
If I send a mail to my adress at @web.de with a postfix simplified mailbox 
command NOT containing the mailbox with "-m", then mail is send to web.de and 
there I receive it in the incoming box. This is the simplified command:
mailbox_command = /usr/lib/dovecot/dovecot-lda -f "$SENDER" -a "$RECIPIENT"

Summary:
All examples from above show that I do not get a COPY of the outgoing mail in 
my "SENT" folder but it's the REAL mail. 

Can You please give me some advice what to do?

Thank You!

Wolfgang

P.S.: In /var/log/mail and /var/log/dovecot.log I do not get any errors.