What is the maximum length of a valid email address

Question

What is the maximum length of a valid email address  Is it defined by any standard

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TLDR Answer Given an email address like    me example com  The length limits are as follows   Entire Email Address  aka   quot The Path quot    i e   me example com -- 256 characters maximum  Local-Part  i e   me -- 64 character maximum  Domain  i e   example com -- 254 characters maximum   Source SMTP originally defined what a path was in RFC821  published August 1982  which is an official Internet Standard  most RFC s are only proposals    To quote it        a reverse-path  specifies who the mail is from     a forward-path  which specifies who the mail is to   RFC2821  published in April 2001  is the Obsoleted Standard that defined our present maximum values for local-parts  domains  and paths   A new Draft Standard  RFC5321  published in October 2008  keeps the same limits   In between these two dates  RFC3696 was published  on February 2004   It mistakenly cites the maximum email address limit as 320-characters  but this document is  quot Informational quot  only  and states   quot This memo provides information for the Internet community   It does not specify an Internet standard of any kind  quot   So  we can disregard it  To quote RFC2821  the modern  accepted standard as confirmed in RFC5321     4 5 3 1 1   Local-part The maximum total length of a user name or other local-part is 64 characters  4 5 3 1 2   Domain The maximum total length of a domain name or number is 255 characters  4 5 3 1 3   Path The maximum total length of a reverse-path or forward-path is 256 characters  including the punctuation and element separators    You ll notice that I indicate a domain maximum of 254 and the RFC indicates a domain maximum of 255   It s a matter of simple arithmetic   A 255-character domain  plus the  quot   quot  sign  is a 256-character path  which is the max path length   An empty or blank name is invalid  though  so the domain actually has a maximum of 254

User · Answer

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

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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

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user      The maximum total length of a user name is 64 characters       domain      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       lt       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

User · Answer

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

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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

User · Answer

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

User · Answer

According to the below article  http   tools ietf org html rfc3696  Page 6  Section 3  It s mentioned that    quot There is a length limit on email addresses   That limit is a maximum of 64 characters  octets  in the  quot local part quot   before the  quot   quot   and a maximum of 255 characters  octets  in the domain part  after the  quot   quot   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  quot   So  the maximum total length for an email address is 320 characters   quot local part quot   64    quot   quot   1    quot domain part quot   255 which sums to 320

User · Answer

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     lt     A-d-l       Mailbox   gt     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      The maximum total length of a reverse-path or forward-path is 256 characters    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

User · Answer

TLDR Answer Given an email address like    me example com  The length limits are as follows   Entire Email Address  aka   quot The Path quot    i e   me example com -- 256 characters maximum  Local-Part  i e   me -- 64 character maximum  Domain  i e   example com -- 254 characters maximum   Source SMTP originally defined what a path was in RFC821  published August 1982  which is an official Internet Standard  most RFC s are only proposals    To quote it        a reverse-path  specifies who the mail is from     a forward-path  which specifies who the mail is to   RFC2821  published in April 2001  is the Obsoleted Standard that defined our present maximum values for local-parts  domains  and paths   A new Draft Standard  RFC5321  published in October 2008  keeps the same limits   In between these two dates  RFC3696 was published  on February 2004   It mistakenly cites the maximum email address limit as 320-characters  but this document is  quot Informational quot  only  and states   quot This memo provides information for the Internet community   It does not specify an Internet standard of any kind  quot   So  we can disregard it  To quote RFC2821  the modern  accepted standard as confirmed in RFC5321     4 5 3 1 1   Local-part The maximum total length of a user name or other local-part is 64 characters  4 5 3 1 2   Domain The maximum total length of a domain name or number is 255 characters  4 5 3 1 3   Path The maximum total length of a reverse-path or forward-path is 256 characters  including the punctuation and element separators    You ll notice that I indicate a domain maximum of 254 and the RFC indicates a domain maximum of 255   It s a matter of simple arithmetic   A 255-character domain  plus the  quot   quot  sign  is a 256-character path  which is the max path length   An empty or blank name is invalid  though  so the domain actually has a maximum of 254

User · Answer

The other answers muddy the water a bit   Simple answer  254 total chars in our control for email 256 are for the ENTIRE email address  which includes implied   lt   at the beginning  and     at the end  Therefore  254 are left over for our use

User · Answer

user      The maximum total length of a user name is 64 characters       domain      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       lt       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

User · Answer

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     lt     A-d-l       Mailbox   gt     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      The maximum total length of a reverse-path or forward-path is 256 characters    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

User · Answer

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

User · Answer

According to the below article  http   tools ietf org html rfc3696  Page 6  Section 3  It s mentioned that    quot There is a length limit on email addresses   That limit is a maximum of 64 characters  octets  in the  quot local part quot   before the  quot   quot   and a maximum of 255 characters  octets  in the domain part  after the  quot   quot   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  quot   So  the maximum total length for an email address is 320 characters   quot local part quot   64    quot   quot   1    quot domain part quot   255 which sums to 320

User · Answer

The other answers muddy the water a bit   Simple answer  254 total chars in our control for email 256 are for the ENTIRE email address  which includes implied   lt   at the beginning  and     at the end  Therefore  254 are left over for our use

[validation] What is the maximum length of a valid email address?

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