Thanks for all your comments, and sorry for my slow response.
I will explain the situation to all your comments.
Below are the situations and concerns that I reconfirmed.
First, the auto directory I installed doesn't contain Encode.dll, it has Encode.xs.dll instead.
Is this correct?
And I have the following concerns.
When I installed Encode 2.87 with Perl on Windows10/XAMPP(standard Encode version: 3.08) by running "perl makefile.pl prefix='c:\xampp\perl\lib_ext'","gmake","gmake test","gmake install" , the following folders/files were generated.

c:\xampp\perl----\lib
              |--\lib_ext----\bin
                          |--\lib----\auto----\Encode---- Encode.xs.dl
+l
                                  |                   |-- .paclist
                                  |                   |--\Byte
                                  |                   |-- (\JP/\EBCDIC
+/...another folder)
                                  |
                                  |--\Encode---- Alias.pm
                                  |          |-- Byte.pm
                                  |          |-- Config.pm
                                  |          |-- EBCDIC.pm
                                  |          |-- encode.h
                                  |          |-- Encoder.pm
                                  |          |-- Encoding.pm
                                  |          |-- JP.pm
                                  |          |-- (Another file)
                                  |
                                  |
                                  |-- Encode.pm
                                  |-- encoding.pm
                                  |-- perllocal.pod
[download]

Then I copied these to the following directory on the web server(Linux).

/home/users/0/usrxxxx/web/usr/bin----/lib_ext---- Encode.pm
                                  |           |-- encoding.pm
                                  |           |-- perllocal.pod
                                  |           |
                                  |           |-- /auto----/Encode----
+ Encode.xs.dll
                                  |           |                    |--
+ .paclist
                                  |           |                    |--
+/Byte
                                  |           |                    |--
+ (\JP/\EBCDIC/...another folder)
                                  |           |
                                  |           |-- /Encode---- Alias.pm
                                  |                       |-- Byte.pm
                                  |                       |-- Config.p
+m
                                  |                       |-- EBCDIC.p
+m
                                  |                       |-- encode.h
                                  |                       |-- Encoder.
+pm
                                  |                       |-- Encoding
+.pm
                                  |                       |-- JP.pm
                                  |                       |-- (Another
+ file)
                                  |
                                  |--( /target directory ---- target s
+cript )
[download]

As a result, I got the following error(same as 2nd error) when running the script:

-- Error3:
Encode object version 2.68 does not match bootstrap parameter 2.87 at 
+/usr/local/perl/5.10/lib/5.10.1/x86_64-linux-thread-multi/DynaLoader.
+pm line 223.
[download]

The error when using the server's standard module Encode.pm 2.68 was the 1st error (Encode version 2.87 required--this is only version 2.68 at ../lib_ext/Email/MIME/ContentType.pm line 7.) I posted, but the error after copying above file/folder was the second Error (Encode object version 2.68 does not match bootstrap parameter 2.87 at /usr/local/perl/5.10/lib/5.10.1/x86_64-linux-thread-multi/DynaLoader.pm line 223.), so I think "use lib qw{../lib_ext};" or "BEGIN { unshift(@INC, "../lib_ext") };" in my script works.
(At least Encode.pm 2.87 is searched, but I think the related files are incorrect. maybe)
Just in case, I also tried "use FindBin qw($RealBin); use lib "$RealBin/../lib_ext";", but the result was the same.

I have the following question now.
I'm very curious what the error on the server, "DynaLoader.pm line 223" means.
In addition, the following error occurred when the same script was executed on Localhost on Windows/xampp.

Can't load '(C:/Users/localhost directry)/usr/bin/target folder/../lib
+_ext/auto/Encode/Encode.xs.dll' for module Encode: load_file: The spe
+cified module could not be found at C:/usr/lib/XSLoader.pm line 93.
 at C:/Users/localhost directry)/usr/bin/mail_rcv_spam/../lib_ext/Enco
+de.pm line 10.
[download]

The "C:/usr/lib/XSLoader.pm line 93" part in this error indicates the path of the standard module of the server.
Is it impossible to use a different Encode module with the same name just by copying the files/folders installed on Winodws/xampp?
Or is my installation/copy work wrong?

Hello soso_ynak. There are several problems here - I will try to explain.

Firstly, your paths suggest that you are using version 5.10.1 of Perl. This is very old indeed. It is so old that I'm unaware of any supported operating system which ships with it any more. It may be that your hosting company's O/S is out of date in which case you might ask them to move you to a supported server instead (and that might solve a lot of the problems).

Secondly, Encode is in core which means it ships with Perl itself. Modifying the versions of core modules without moving to the associated version of Perl may cause problems. You might be lucky but then again you might not.

Finally, Encode is an XS module which means that even if you get the source onto the server and some means to install it you will still either need access to a C compiler on the server or else you will have to cross-compile it, neither of which will likely be easy.

In your position I would contact the hosting company and ask to be moved to a modern O/S with a recent version of Perl and take it from there.

There's actually two directories that need to be added to @INC, the one that allows it to locate the .pm, and the one that allows it to locate the .so. The following will add both:

use FindBin qw( $RealBin );
use lib "$RealBin/../lib_ext";
[download]

(This also removes assumption that the PWD is the directory containing the script.)

There's actually two directories that need to be added to @INC, the one that allows it to locate the .pm, and the one that allows it to locate the .so.

Not in my experience.
If you add a single location to @INC that will locate the .pm file, then that's all you need to do - assuming that you've located the .so in the location (relative to the .pm file) where perl will look for it.
Of course, if you've placed the .so file in some other location (where perl won't look for it) then you will need to add a second path to @INC that will enable the .so file to be found by perl.

I guess you are referring to the latter scenario.

Cheers,
Rob

Yeah, nevermind. Both the pm and so are installed in the arch dir. I was confused. The error actually suggests an incorrectly installed module.

That said, it is usually needed to add both the lib and arch dirs (because there are some modules in one and some modules in the other), and use lib adds both.

Please provide the output of find ../lib_ext.