Document that Django email validator does not enforce valid emails

[James Pic]

Currently, Django makes it seem that using an EmailField / EmailValidator will protect projects from getting invalid emails in their database.

But in reality, users must not count on Django for that:

• https://code.djangoproject.com/ticket/31959
• https://code.djangoproject.com/ticket/25452

This makes the following documentation statement inaccurate:

"EmailField: A CharField that checks that the value is a valid email address using EmailValidator."

Source : ​https://docs.djangoproject.com/en/3.1/ref/models/fields/#emailfield

It would be only fair to users to document that the EmailValidator will let invalid emails through, which will be the cause of SMTPError, and that people who don't want invalid emails in their EmailField must override and fix Django's default behaviour.

As to why EmailValidator would reject emails starting with a dot like ".foo@…" but not emails starting with a hyphen "-foo@…": this will remain a mystery.