Sign-up rejects plus-addressed (subaddressed) email

I’m trying to create a second Netlify account using a plus-addressed (subaddressed) email

e.g. `myname+netlify@example.com`. Plus-addressing is valid per RFC 5321/5322 and I rely on it

to separate accounts that share one inbox. The sign-up flow won’t accept it, in two stages.

Environment

- Page: `app.netlify.com` sign-up (Email provider)

- Browser: Chrome 146 (also reproduced in Firefox), desktop Linux

- Account type: new sign-up, email/password (not SSO)

Steps to reproduce

1. Go to the email sign-up form on `app.netlify.com`.

2. Enter a valid plus-addressed email, e.g. `myname+netlify@example.com`.

3. Enter a password.

4. Submit.

Expected

Account is created (or a verification email is sent), since `+` is a valid, common email format.

Actual two separate blocks

1. Front-end validation flags the field with “Email address is invalid” before submit,

purely because of the `+` character. (A plain `myname@example.com` is accepted, so it’s the

`+` specifically.)

2. If the value is entered another way and submitted, the API call to

`POST https://api.netlify.com/auth/signup?provider=email…` returns **HTTP 403** with a

plain-text body `Forbidden`. (reCAPTCHA Enterprise is present on the page.)

What I’ve tried

- Confirmed the same address works as a recipient (mail to `myname+netlify@…` is delivered).

- Tried Chrome and Firefox — same front-end rejection.

- Confirmed a non-plus address on the same domain registers fine.

Question

- Is plus-addressed email intentionally unsupported at sign-up, or is this a validation bug?

- If unsupported, what’s the recommended way to create a second account that shares one

inbox? (Is there an invite/team flow, or an alternate sign-up path, that accepts `+` emails?)

Thanks! Happy to provide a HAR or screenshots if useful.