[Koha] OPAC problem

[vijay kumar]

Dear MEMBER,
1)Actually I upgraded my koha version from koha3 beta2 to koha 3 latest.
So I installed all perl module and cpan module required for koha 3 latest.
 I tried manually to install MIME-Lite beside through CPAN
installation. but I am unable to install MIME-Lite-3.021
Meanwhile  I had upgraded my koha-3 beta2 version  to koha-3 latest.

2) When I checked in ABOUT KOHA==>perl module showing
MIME::Lite module is missing
And when I run this command
 perl -M'MIME::Lite' -e print
showing
can't find an executable sendmail at -e line 0
Compilation failed in require.
BEGIN failed--compilation aborted.

3)I am able to add records through z3950 but I am unable to see latest
added records.
  Old records are retrievable on OPAC
4)Now  I am unable to get my OPAC.When I searched my record it retrieves.
When I click on any record  gives error..........

[Screenshot]
Koha error

The following fatal error has occurred:

can't find an executable sendmail at /usr/share/koha/lib/C4/Letters.pm line 21
Compilation failed in require at /usr/share/koha/lib/C4/Letters.pm line 21.
BEGIN failed--compilation aborted at /usr/share/koha/lib/C4/Letters.pm line 21.
Compilation failed in require at /usr/share/koha/lib/C4/Serials.pm line 30.
BEGIN failed--compilation aborted at /usr/share/koha/lib/C4/Serials.pm line 30.
Compilation failed in require at
/usr/share/koha/opac/cgi-bin/opac/opac-detail.pl line 27.
BEGIN failed--compilation aborted at
/usr/share/koha/opac/cgi-bin/opac/opac-detail.pl line 27.

Apache	Server version: Apache/2.2.8 (Ubuntu) Server built: Jun 25 2008 13:50:52
Koha	3.00.00.107
Koha DB	3.0000107
MySQL	mysql Ver 14.12 Distrib 5.0.51a, for debian-linux-gnu (i486)
using readline 5.2
OS	Linux sri-home 2.6.24-16-generic #1 SMP Thu Apr 10 13:23:42 UTC
2008 i686 GNU/Linux
Perl	5.008008

Please help to find out this problem....
Thanks,
Vijay Kumar