DEMO PROJECT

RFC 5321 - https://datatracker.ietf.org/doc/html/rfc5321 p. 4.5.3.1.1-4.5.3.1.3
see also: https://datatracker.ietf.org/doc/html/rfc5322 p. 3.4.1.

4.5.3.1.1.  Local-part

   The maximum total length of a user name or other local-part is 64
   octets.

4.5.3.1.2.  Domain

   The maximum total length of a domain name or number is 255 octets.

4.5.3.1.3.  Path

   The maximum total length of a reverse-path or forward-path is 256
   octets (including the punctuation and element separators).