RegEx in Python for word boundary

import re

pattern = re.compile(r"(^|(?<=\s))[a-zA-Z0-9]+[\-_\.]*\w+@\w+[\-_\.]*\w+\.[\w\.]+\b")
text = input()

matches = pattern.finditer(text)
for match in matches:
    print(match.group())


# valid emails: [email protected],
# [email protected], [email protected],
# [email protected], [email protected].

# invalid emails: [email protected], …@mail.bg,
# [email protected], [email protected], mike@helloworld, [email protected]., s.johnson@invalid-.