Acceptable field type and size for email address? [duplicate]

According to RFC 5321, forward and reverse path can be up to 256 chars long, so the email address can be up to 254 characters long. You're safe with using 255 chars.

RFC5321 and RFC5322, the relevant standards for SMTP, specify that an address consists of a local part and a domain. They further state that the maximum sizes for those are respectively 64 and 253 octets, though there's a further 256-octet limit imposed by the forward and reverse paths, including the punctuation (so 254 in reality).

So that should be all that you need for that.

standard in any enterprise web application is varchar with 255 length

  varchar(255)