Warning: Ignoring deprecated 'login' section handling. Use protocol imap/pop3 { .. } instead. Some settings may have been read incorrectly.
Warning: Ignoring deprecated 'login' section handling. Use protocol imap/pop3 { .. } instead. Some settings may have been read incorrectly.
Error: Can't use mail executable /usr/lib/dovecot/imap: No such file or directory


#########

And then i installed dovecot-imapd dovecot-pop3d with apt-get, it says now:
apt-get install dovecot-imapd dovecot-pop3d
Reading Package Lists... Done
Building Dependency Tree... Done
The following NEW packages will be installed:
  dovecot-imapd dovecot-pop3d
0 upgraded, 2 newly installed, 0 to remove and 155 not upgraded.
Need to get 1122kB of archives.
After unpacking 1909kB of additional disk space will be used.
Get:1 http://ftp.fi.debian.org unstable/main dovecot-imapd 1:1.0.0-1 [578kB]
Get:2 http://ftp.fi.debian.org unstable/main dovecot-pop3d 1:1.0.0-1 [544kB]
Fetched 1122kB in 0s (4594kB/s)
Selecting previously deselected package dovecot-imapd.
(Reading database ... 35907 files and directories currently installed.)
Unpacking dovecot-imapd (from .../dovecot-imapd_1%3a1.0.0-1_i386.deb) ...
Selecting previously deselected package dovecot-pop3d.
Unpacking dovecot-pop3d (from .../dovecot-pop3d_1%3a1.0.0-1_i386.deb) ...
Setting up dovecot-imapd (1.0.0-1) ...
Starting mail server: dovecotWarning: Ignoring deprecated 'login' section handling. Use protocol imap/pop3 { .. } instead. Some settings may have been read incorrectly.
Warning: Ignoring deprecated 'login' section handling. Use protocol imap/pop3 { .. } instead. Some settings may have been read incorrectly.
.

Setting up dovecot-pop3d (1.0.0-1) ...
Starting mail server: dovecotWarning: Ignoring deprecated 'login' section handling. Use protocol imap/pop3 { .. } instead. Some settings may have been read incorrectly.
Warning: Ignoring deprecated 'login' section handling. Use protocol imap/pop3 { .. } instead. Some settings may have been read incorrectly.
.