U is a letter, it does not mean you. Ur is Abraham's first home, not an acceptable way of writing your. Spell check is a necessity in all emails. No exceptions.
Typos are one thing and can be forgiven. Texting on your phone is also different as writing words is annoying on a 9 key pad and there is no spell check.
But in an email, the inability to spell words and use spell check and the unnecessary abbreviation of pronouns is a transgression in which forgiveness could be questionable.
Misspelling words in an email to someone you don't know/barely know/want to impress/ask a favor of/communicate with in a socially acceptable way is like urging the recipient of said poorly written email to dismiss you like the smelly kid in math class.
That's right kids, bad grammar is the B.O. of internet land.
Happy spell checking.