If you're trying on RHEL to install mailsync for IMAP stuff and it needs the MailClient rpm but won't install it because
it keeps saying you need sometihng called perl Parse::Descent....

install it from manual by downloading with wget and running rpm -i

and what took so long was needing to get the LATEST VERSION which we found here:

https://centos.pkgs.org/7/centos-x86_64/perl-Parse-RecDescent-1.967009-5.el7.noarch.rpm.html

Even though we're running RHEL 7 something, it works with centos I think. Haven't tested, but installed it said fine and with all other dependencies.