阅读： http://www.eph.co.uk/resources/email-address-length-faq/
其结果是您应该使用254个字符来存储电子邮件地址，因为这是SMTP事务中允许的最大值。这在RFC5321（您的文章中这样说，实际上是在我的引用）中指定，这是权威性的。

Read this: http://www.eph.co.uk/resources/email-address-length-faq/ The upshot of it is that you should use 254 characters to store email addresses, because that is the maximum allowed in an SMTP transaction. This is specified in RFC5321 (your article says so, and is actually quoted in mine), which is authoritative.