A ”wall of text” is a term referring to a dense block of text, void of any breathing-space - both literally and figuratively. This way of writing might be appropriate in a novel, but when it comes to emailing it only gives the recipient a headache.

Allow for the segments to be shorter than if you had written a text intended to be printed before being read. Reading texts on screens is often perceived as much more strenuous than reading a text you have printed out.

If you want, do this
Today I would like you to exaggerate when subdividing your emails. Let today’s mottos be ”Space” and ”Subdivide”. No one will complain if you adopt this habit.