如何从文本文件中提取特定电子邮件

@JAW对这个问题绝对正确,因为你正在逐行搜索它。因为你正在使用 re.findall ,没有理由需要遍历这些行。你所要做的就是:

import re

filename = input('Enter filename to open: ')

try:
    file = open(filename)
except:
    print('File cannot be opened: ', filename)
    exit()

emails = file.read()
x = re.findall('\S+@gmail.com',  emails)
if len(x) > 0:
    print(x)
    # or print("\n".join(x)) for list-like printing 

y = re.findall('\S+@hotmail.com',  emails)
if len(y) > 0:
    print(y)
    # or print("\n".join(y)) for list-like printing

gmail = []
hotmail = []

for line in filename: #filename is a BAD name for this variable
    address = re.findall('\S+@gmail.com', line)
    if address: gmail.extend(address)
    address = re.findall('\S+@hotmail.com', line)
    if address: hotmail.extend(address)

print(gmail)
print(hotmail)