R1:6f21cfbe10a6

trivial typo

Summary: There is a typo in one of the example mail test commands.

Test Plan: Read the command, maybe even paste it.

Reviewers: #blessed_reviewers, epriestley

Reviewed By: #blessed_reviewers, epriestley

Subscribers: joshuaspence, epriestley

Differential Revision: https://secure.phabricator.com/D10072