What is the maximum length of a valid email address? Is it defined by any standard?
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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
So the Mailbox element (i.e., 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:
RFC 3696 was corrected here.
People should be aware of the errata against RFC 3696 in particular. Three of the canonical examples are in fact invalid addresses.
I’ve collated a couple hundred test addresses, which you can find at http://www.dominicsayers.com/isemail