Drupal cant find PEAR Mail_mimeDecode

I am trying to use og_mailinglist on a shared server along with mailgun.

On my site's status report I see:

The Mail_mimeDecode PEAR extension is missing or not installed correctly. Check that the extension is installed and that your PHP include_path is correct. See the INSTALL.txt file for more information at path/to/drupal/sites/all/modules/og_mailinglist/INSTALL.txt.

PEAR seems to be installed on the shared server, as pear config-show gives this:

Auto-discover new Channels auto_discover
Default Channel default_channel pear.php.net
HTTP Proxy Server Address http_proxy
PEAR server [DEPRECATED] master_server pear.php.net
Default Channel Mirror preferred_mirror pear.php.net
Remote Configuration File remote_config
PEAR executables directory bin_dir /usr/local/bin
PEAR documentation directory doc_dir /usr/local/lib/php/docs
PHP extension directory ext_dir /usr/local/lib/php/extensions/no-debug-non-zts-20060613
PEAR directory php_dir /usr/local/lib/php
PEAR Installer cache directory cache_dir /tmp/pear/cache
PEAR configuration file cfg_dir /usr/local/lib/php/cfg
directory
PEAR data directory data_dir /usr/local/lib/php/data
PEAR Installer download download_dir /tmp/pear/download
directory
PHP CLI/CGI binary php_bin /usr/local/bin/php
php.ini location php_ini
--program-prefix passed to php_prefix
PHP's ./configure
--program-suffix passed to php_suffix
PHP's ./configure
PEAR Installer temp directory temp_dir /tmp/pear/temp
PEAR test directory test_dir /usr/local/lib/php/tests
PEAR www files directory www_dir /usr/local/lib/php/www
Cache TimeToLive cache_ttl 3600
Preferred Package State preferred_state stable
Unix file mask umask 2
Debug Log Level verbose 1
PEAR password (for password
maintainers)
Signature Handling Program sig_bin /usr/bin/gpg
Signature Key Directory sig_keydir /usr/local/etc/pearkeys
Signature Key Id sig_keyid
Package Signature Type sig_type gpg
PEAR username (for username
maintainers)
User Configuration File Filename /home/jonathan/.pearrc
System Configuration File Filename /usr/local/etc/pear.conf

I have also tried adding Mail_mimeDecode to sites/all/libraries while using the libraries module, but that also didn't work.

What do I need to do to get PEAR working properly with og_mailinglist?

Thanks.