EmailStr is not case-sensitive on local part of email per RFC 5321

[henriklindgren]

Bug

EmailStr validate-method performs lower() on whole string including local part, violating RFC 5321 by not conforming to

The local-part of a mailbox MUST BE treated as case sensitive.
https://tools.ietf.org/rfc/rfc5321.txt

See
https://github.com/samuelcolvin/pydantic/blob/79017111aa030873f2dc54576e2c768d154b1be5/pydantic/networks.py#L383

• OS: Any
• Python version import sys; print(sys.version): Any
• Pydantic version import pydantic; print(pydantic.VERSION): 0.32.2

Where possible please include a self contained code snippet describing your bug:

import pydantic
assert pydantic.EmailStr.validate('AbC@example.com') == 'AbC@example.com'

[samuelcolvin]

Thanks for reporting, PR welcome to fix this.

[dmontagu]

Closing as it looks like this was addressed by #801. Thanks for the contribution @henriklindgren!

[slavugan]

this RFC 5321 looks outdated as most email services works with emails as case insensitive, and following this RFC just complicates our life. just IMHO.

[emilpaw]

Is there a simple way to get the old behavior back?

[myrataltyyev]

If you want case insensitive email, inherit EmailStr and convert the value to lowercase.

class CustomEmailStr(EmailStr):
    @classmethod
    def validate(cls, value: EmailStr) -> EmailStr:
        email = validate_email(value)[1]
        return email.lower()

Note: validate method overrode the EmailStr's validate method. That's why had to include the lines of the EmailStr validation.

[amirsoroush]

If you want case insensitive email, inherit EmailStr and convert the value to lowercase.

class CustomEmailStr(EmailStr):
    @classmethod
    def validate(cls, value: EmailStr) -> EmailStr:
        email = validate_email(value)[1]
        return email.lower()

Note: validate method overrode the EmailStr's validate method. That's why had to include the lines of the EmailStr validation.

It's now called _validate():

https://github.com/pydantic/pydantic/blob/main/pydantic/networks.py#L418