#coding=utf-8
import re
a=re.compile(r'(?:^|[^\w])@(\w+)')
print a.findall('@whtsky,邮箱地址是ta@g.com 已经给@gdjm发了一封信.Never fall in love with @china.我想看看@luztak')

['whtsky', 'gdjm', 'china', 'luztak']