What is the maximum length of a valid email address?
What is the maximum length of a valid email address? Is it defined by any standard?
An email address must not exceed 254 characters.
This was accepted by the IETF following submitted erratum. A full diagnosis of any given address is available online. The original version of RFC 3696 described 320 as the maximum length, but John Klensin subsequently accepted an incorrect value, since a Path is defined as
Path = "<" [ A-d-l ":" ] Mailbox ">"
So the Mailbox element (ie, the email address) has angle brackets around it to form a Path, which a maximum length of 254 characters to restrict the Path length to 256 characters or fewer.
The maximum length specified in RFC 5321 states:
The maximum total length of a reverse-path or forward-path is 256 characters.
RFC 3696 was corrected here.
I've now collated test cases from Cal Henderson, Dave Child, Phil Haack, Doug Lovell and RFC 3696. 158 test addresses in all.
I ran all these tests against all the validators I could find. The comparison is here: http://www.dominicsayers.com/isemail
I'll try to keep this page up-to-date as people enhance their validators. Thanks to Cal, Dave and Phil for their help and co-operation in compiling these tests and constructive criticism of my own validator.
People should be aware of the errata against RFC 3696 in particular. Three of the canonical examples are in fact invalid addresses.
320
And the segments look like this
{64}@{255}
64 + 1 + 255 = 320
You should also read this if you are validating emails
http://haacked.com/archive/2007/08/21/i-knew-how-to-validate-an-email-address-until-i.aspx
To help the confused rookies like me, the answer to "What is the maximum length of a valid email address?" is 254 characters .
If your application uses an email, just set your field to accept 254 characters or less and you are good to go.
You can run a bunch of tests on an email to see if it is valid here. http://isemail.info/
The RFC, or Request for Comments is a type of publication from the Internet Engineering Task Force (IETF) that defines 254 characters as the limit. Located here - https://tools.ietf.org/html/rfc5321#section-4.5.3
链接地址: http://www.djcxy.com/p/1118.html下一篇: 什么是有效的电子邮件地址的最大长度？