1.Login to your server console as root

# yum install re2c
# yum install lsphp70-devel make gcc glibc-devel zlib-devel
# /usr/local/lsws/lsphp70/bin/pecl install mailparse
# chmod 755 /usr/local/lsws/lsphp70/lib64/php/modules/*

3 - IMPORTANT : we need to create a "mailparse.ini" to load as
module in php, but the "mbstring" extension must to be loaded

BEFORE the "mailparse" extension.
In /usr/local/lsws/lsphp70/etc/php.d/ you can see all the extensions to
be loaded by php, normally with a number like 00- or 20- etc. That
number indicates the PRIORITY of loading.

In my case the mbstring is :
/usr/local/lsws/lsphp70/etc/php.d/20-mbstring.ini

SO, to create the mailparse ini there, i need to create it with 30- (to
load it AFTER mbstring), THEN....

# echo "extension=mailparse.so" >
/usr/local/lsws/lsphp70/etc/php.d/30-mailparse.ini

and finally :

# systemctl restart lsws