[Validation] What is the maximum length of a valid email address?
And the segments look like this
64 + 1 + 255 = 320
You should also read this if you are validating emails
What is the maximum length of a valid email address? Is it defined by any standard?
According to the below article:
http://tools.ietf.org/html/rfc3696 (Page 6, Section 3)
It's mentioned that:
"There is a length limit on email addresses. That limit is a maximum of 64 characters (octets) in the "local part" (before the "@") and a maximum of 255 characters (octets) in the domain part (after the "@") for a total length of 320 characters. Systems that handle email should be prepared to process addresses which are that long, even though they are rarely encountered."
So, the maximum total length for an email address is 320 characters ("local part": 64 + "@": 1 + "domain part": 255 which sums to 320)
The maximum total length of a user name is 64 characters.
Maximum of 255 characters in the domain part (the one after the “@”)
However, there is a restriction in RFC 2821 reading:
The maximum total length of a reverse-path or forward-path is 256 characters, including the punctuation and element separators”. Since addresses that don’t fit in those fields are not normally useful, the upper limit on address lengths should normally be considered to be 256, but a path is defined as: Path = “<” [ A-d-l “:” ] Mailbox “>” The forward-path will contain at least a pair of angle brackets in addition to the Mailbox, which limits the email address to 254 characters.