I get frustrated by badly written email. Whether the person doesn’t care enough to be clear, or is just being rude, or is unintentionally vague, it makes it hard to respond appropriately.
If you think I’m talking about you (and I may be), you should read Email: an author’s guide to get some ideas on how to improve.
I guess you’re referring to those people that use the text talk. For example “btw u r gr8 4eva.” People should write an email like they are writing a letter. If they don’t know how to do that then shame on our education system.