Why do websites disallow the plus sign in e-mails [closed]

1. Are plus signs allowed in emails?
2. Does Gmail ignore plus sign?
3. What happens when you add a plus in the email?

Are plus signs allowed in emails?

Using plus addresses

You can use plus addresses as unique addresses for services that you sign up for. You cannot, however, send from plus addresses. Some web forms don't support plus signs in email addresses.

Does Gmail ignore plus sign?

Plus Signs: Plus Signs are also ignored in any Gmail address, along with anything that comes after the plus sign, up to the @ symbol. That means you can customize your email address with any words you like.

What happens when you add a plus in the email?

Email subaddressing, also known as plus sign (+) trick, is popularized by Gmail and now supported by most email providers. It allows creating a new email address by simply appending the plus sign(+) to your current email address.