@contextmanager
def smtp_connection(host, user=None, passwd=None, timeout=5):
    conn = None # smell here
    try:
        conn = SMTP(host=host, timeout=timeout)
        conn.ehlo_or_helo_if_needed()
        if user and passwd:
            conn.login(user=user, password=passwd)
        logger.debug('SMTP connected')
        yield conn
    except Exception as e:
        raise e
    finally:
        if conn: # and here
            conn.quit()

with ExitStack() as stack:
    stack.callback(cleanup_resources)
    result = perform_operation()
    if result:
        stack.pop_all()

with ExitStack() as stack:
    result = None
    stack.callback(lambda conn: conn.quit())
    result = POP3() # code from above here
    if result:
        stack.pop_all()

except Exception as e:
    raise e

except Exception:
    raise

@contextmanager
def smtp_connection(host, user=None, passwd=None, timeout=5):
    conn = SMTP(host=host, timeout=timeout)
    try:
        conn.ehlo_or_helo_if_needed()
        if user and passwd:
            conn.login(user=user, password=passwd)
        logger.debug('SMTP connected')
        yield conn
    finally:
        conn.quit()

@contextmanager
def smtp_connection(host, timeout):
    connection = SMTP(host=host, timeout=timeout)
    yield connection
    connection.quit()

@contextmanager
def smtp_setup(host, user=None, passwd=None, timeout=5):
    with smtp_connection(host, timeout) as conn:
        conn.ehlo_or_helo_if_needed()
        if user and passwd:
            conn.login(user=user, password=passwd)
        logger.debug('SMTP connected')
        yield conn

@contextmanager
def smtp_connection(host, timeout):
    connection = SMTP(host=host, timeout=timeout)
    yield connection
    connection.quit()

def smtp_setup(conn, user=None, passwd=None):
    conn.ehlo_or_helo_if_needed()
    if user and passwd:
        conn.login(user=user, password=passwd)
    logger.debug('SMTP connected')

with smtp_connection(h, u, p, t) as conn:
    # do stuff

with smtp_connection(h, t) as conn:
    smtp_setup(conn, u, p)
    # do stuff