<p>I sent my professor an email yesterday because he gave me the wrong grade. I sent it yesterday .. I know he checks his email a lot. How long should I wait?</p>
<p>Some things should be done in person - with the evidence in hand. </p>
<p>Go in person.
Otherwise, the norm is 48h, so if you sent it on May 15th, you have to give the professor until May 17th before you call. If school is out, your professor may be away, out of the country, doing research somewhere, etc.</p>