I will make my question simple.
when writing a formal email, is it ok to use contractions? or is it unprofessional?
For example, can I write:
"I haven't received your email." instead of "I have not received your email."
This subject is debatable. My advice is to not use contractions when writing a formal email/letter.
I remember in college, my English teacher would remind us not to use contractions when writing.