我在这里看到了很多复杂的答案。他们中的一些人，不知道简单，真实的电子邮件地址，或有假阳性。下面是测试字符串是否为有效电子邮件的最简单方法。它测试2和3个字母的TLD。现在技术上你可以有更大的，你可能希望增加3到4,5甚至10。

import re
def valid_email(email):
  return bool(re.search(r"^[\w\.\+\-]+\@[\w]+\.[a-z]{2,3}$", email))

电子邮件地址非常复杂。下面是一个匹配每个rfc822有效地址的示例正则表达式: http://www.ex-parrot.com/pdw/Mail-RFC822-Address.html

您会注意到它可能比程序的其他部分要长。甚至还有用于验证电子邮件地址的Perl完整模块。所以你可能不会得到任何东西，100%完美的正则表达式，同时也可读。下面是一个递归下降解析器示例: http://cpansearch.perl.org/src/ABIGAIL/RFC-RFC822-Address-2009110702/lib/RFC/RFC822/Address.pm

但是您需要决定是需要完美的解析还是简单的代码。

我还没有在这里的一堆自定义正则表达式答案中看到答案，但是……

存在一个名为py3-validate-email validate_email的python库，它有3个级别的电子邮件验证，包括询问有效的SMTP服务器电子邮件地址是否有效(不发送电子邮件)。

安装

python -m pip install py3-validate-email

基本用法:

from validate_email import validate_email
is_valid = validate_email(email_address='example@example.com', \
    check_regex=True, check_mx=True, \
    from_address='my@from.addr.ess', helo_host='my.host.name', \ 
    smtp_timeout=10, dns_timeout=10, use_blacklist=True)

对于那些对肮脏细节感兴趣的人，validate_email.py (source)旨在忠实于RFC 2822。

我们所做的只是将输入字符串与1进行比较 庞大的正则表达式。但是构建那个regexp 通过组装它，可以更容易地确保其正确性 从RFC定义的“令牌”。每一个符号都是 在附带的单元测试文件中测试。

你可能需要pyDNS模块来检查SMTP服务器

pip install pyDNS

或者来自Ubuntu

apt-get install python3-dns

我发现了一个很好的(经过测试的)方法来检查有效的电子邮件地址。我把代码粘贴在这里:

# here i import the module that implements regular expressions
import re

# here is my function to check for valid email address
def test_email(your_pattern):
  pattern = re.compile(your_pattern)
  # here is an example list of email to check it at the end
  emails = ["john@example.com", "python-list@python.org", "wha.t.`1an?ug{}ly@email.com"]
  for email in emails:
    if not re.match(pattern, email):
        print "You failed to match %s" % (email)
    elif not your_pattern:
        print "Forgot to enter a pattern!"
    else:
        print "Pass"

# my pattern that is passed as argument in my function is here!
pattern = r"\"?([-a-zA-Z0-9.`?{}]+@\w+\.\w+)\"?"   

# here i test my function passing my pattern
test_email(pattern)

"^[\w\.\+\-]+\@[\w]+\.[a-z]{2,3}$"

The only really accurate way of distinguishing real, valid email addresses from invalid ones is to send mail to it. What counts as an email is surprisingly convoluted ("John Doe" <john.doe@example.com>" actually is a valid email address), and you most likely want the email address to actually send mail to it later. After it passes some basic sanity checks (such as in Thomas's answer, has an @ and at least one . after the @), you should probably just send an email verification letter to the address, and wait for the user to follow a link embedded in the message to confirm that the email was valid.