Incorrect default email length 255.

[jenstroeger]

The default length of a string to store an email is currently 255:

sqlalchemy-utils/sqlalchemy_utils/types/email.py

Line 38 in 5c4ca8c

def __init__(self, length=255, *args, **kwargs):

However, according to the RFC and also this discussion the maximum length of an email address is 254:

In addition to restrictions on syntax, 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. However, there is a restriction in RFC 2821 on the length of an
address in MAIL and RCPT commands of 254 characters. Since addresses
that do not fit in those fields are not normally useful, the upper
limit on address lengths should normally be considered to be 254.

This is probably not a big issue but should be considered for accuracy’s sake.

(See also related old PR #230.)

[kurtmckee]

Because the default is close to but not less than the maximum; and because this is a default that can be changed as needed; and because this default has been deployed for several years; I don't currently see a reason to decrease the default to 254.

[jenstroeger]

Hmm… ok. Keeping in mind, though, that the current default enables people to store invalid email addresses, i.e. one character too long.

[kurtmckee]

It's also possible that people might store things that are convenient to store as email addresses but aren't guaranteed to be. For example, a service may want to store author email addresses listed in git commits, which may not be valid email addresses.

Developers will simply need to control their inputs and requirements. Enforcement shouldn't happen from the database layer.

[jenstroeger]

Yeah the problem of “syntactically correct” email address vs. “valid” actual email address.

Developers will simply need to control their inputs and requirements. Enforcement shouldn't happen from the database layer.

I kind-of agree, though my OCD-driven nit-picking engineering attitude squirms a bit 😉 I’m using EmailType(length=254) and thought I’d prettify that by fixing the default length. Ah so.