Locate your citation for an email reference as close to the information you are using as possible. APA style treats emails as a form of personal communication, such as an interview.
Include the entire citation in parentheses at the end of the sentence where the information you are referencing is located. Follow the following format, as adapted from the Purdue University Online Writing Lab (OWL) website:
The foundation rejected more than half of the applications it received (K. Frog, personal communication, April 1, 2010).
Merge the name of the person you received the email from with the information you are borrowing:
K. Frog claims that the foundation accepted only 45 percent of grant applications (personal communication, April 1, 2010).