import re

parts = ["@gmail", "@cngmail.", "google", "hotmail"]

test = "name@gmail.com,  "
test2 = test.replace(" ","").replace(",","")
#cut-off comma and whitespaces at the end

print(test2)   # name@gmail.com
print(parts[0]) # @gmail

print(parts[0] in test2)
print(re.search(parts[0], test2))
print(test2.rfind(parts[0]))

name@gmail.com
@gmail

False
None
-1