Clicking on mails Selenium

Here find_elements_* will give a list of all found elements, where find_element_* will return only the first find. So try:

driver.find_element_by_partial_link_text("Email Test").click() 

Otherwise, if you want to iterate over the list and click all:

for link in driver.find_elements_by_partial_link_text("Email Test"):
  link.click()