Upgrade to PHP 7.x
 Before PHP upgrade, roundcubemail (under php 5.x) with its dependencies should be 
 removed otherwise failure to load libraries will occur. The 'yum remove' command 
 below (in red) will accomplish this. Reinstall roundcubemail upon upgrade to php 7.x :
 # yum remove git mongodb php-mysql roundcubemail boost-filesystem boost-program-options \
               boost-system boost-thread gperftools-libs libicu libstemmer libxslt perl-Error \
               perl-Git perl-TermReadKey php-gd php-intl php-kolab-net-ldap3 php-ldap php-mbstring \
               php-pdo php-pear php-pear-Auth-SASL php-pear-Mail-Mime php-pear-Net-IDNA2 php-pear-Net-LDAP2 \
               php-pear-Net-SMTP php-pear-Net-Sieve php-pear-Net-Socket php-process php-pspell \
               php-xml t1lib v8 yaml-cpp
 # rpm -ivh https://rpms.remirepo.net/enterprise/remi-release-7.rpm && \
   yum-config-manager --enable remi remi-php73 && \
   yum -y install patch && yum -y update
 
 Upgrade to php 7.x causes QMT Control Panel interfaces 'toaster-admin' and 'mrtg' to fail,
 fix automatically with patches or manually, both procedures below:
 
 Automatic fix w/patch
 # cd /usr/share/toaster/htdocs/mrtg && \
   wget http://www.qmailtoaster.org/index.php.patch && \
   patch < index.php.patch && \
   cd /usr/share/toaster/include && \
   wget http://www.qmailtoaster.org/admin.inc.php.patch && \
   patch < admin.inc.php.patch

 Manual fix         
   In file /usr/share/toaster/htdocs/mrtg/index.php (mrtg) lines 23-25 index.php Patch

   remove:
        eregi($vettore[0] . "(.*)" . $vettore[1] , $contents, $buffer);
        $buffer = ereg_replace("SRC=\"", "src=\"/stats-toaster/?file=", $buffer[1] ) ;
        $buffer = ereg_replace("<HR>", "", $buffer );
   replace:
        preg_match("#" . $vettore[0] . "(.*)" . $vettore[1] . "#s", $contents, $buffer);
        $buffer = preg_replace("/SRC=\"/", "src=\"/stats-toaster/?file=", $buffer[1] ) ;
        $buffer = preg_replace("/<HR>/", "", $buffer );

   In file /usr/share/toaster/include/admin.inc.php (admin-toaster) lines 15 and 16 admin.inc.php Patch

   remove:
        $contents = ereg_replace("\n", "", $contents ) ;
        $contents = ereg_replace("\r", "", $contents ) ;
   replace:
        $contents = preg_replace("\n", "", $contents ) ;
        $contents = preg_replace("\r", "", $contents ) ;