(Adds dropped word "failure" in first paragraph)
VANCOUVER, April 30 (Reuters) - Canada's stock market outage on Friday was caused by hardware failure in a communication management component, according an email reviewed by Reuters.
TMX Group said the "appliance has redundancy built in but when hardware failure occurred redundant communication management module failed to take over primary role," the email sent to clients showed.
TMX did not offer an immediate comment to Reuters' request for comment on the email.
Canadian stock market resumed trading on Monday after Friday's outage. (Reporting by Julie Gordon in Vancover Writing by Denny Thomas Editing by Chizu Nomiyama)