What do I do if webmail is pulling a blank page?

SSH into your server and run the following command:
/usr/local/cpanel/3rdparty/bin/php
The error that is produced should give you library that is missing, such as this:
# /usr/local/cpanel/3rdparty/bin/php
/usr/libexec/ld-elf.so.1: Shared object "libintl.so.4" not found

You would then need to find libintl.so.4 and verify that it is pointing to the right shared library. As we can see from the following example, it is actually pointing to a nonexistant library:

# ls -l libintl*
-rw-r--r-- 1 root wheel 51918 Apr 11 20:16 libintl.a
lrwxr-xr-x 1 root wheel 12 Apr 11 20:16 libintl.so -> libintl.so.6
lrwxr-xr-x 1 root wheel 12 Mar 29 12:26 libintl.so.4 -> libintl.so.5
-r--r--r-- 1 root wheel 38925 Apr 11 20:16 libintl.so.6

To fix this, the following command would be run:
# rm libintl.so.4
# ln -s libintl.so.6 libintl.so.4