(Internet) message instead.
In ordinary language,
email refers both to the system of standards
and to individual messages transmitted via these standards.
While the English language would allow us to distinguish between the two usages
by capitalizing the former but not the latter, I’ve never seen anyone doing this.
Even though I’m tempted to pioneer the proper use of grammar here,
I’d rather save my artistic license for other things.
(Proper nouns refer to a single entity,
whereas common nouns refer to a class of entities.
Only proper nouns are capitalized in English.
For example,
Earth with a capital E refers to the single planet we live on,