Non forwardable email
A "non-forwardable" email is an email that cannot be forwarded to another email address. This is typically done to prevent spam or unwanted emails from being forwarded to other recipients.
There are a few ways to make an email non-forwardable:
- Using a special header: Some email providers, such as Gmail, allow you to add a special header to an email that prevents it from being forwarded. This header is called "X-Fwd-No" and can be added to the email using the following format:
X-Fwd-No: 1. - Using a non-forwardable email address: Some email providers, such as Yahoo!, offer non-forwardable email addresses that cannot be forwarded to other recipients. These addresses typically have a special suffix, such as "@nonforwardable.yahoomail.com".
- Using a mail server configuration: Mail servers can be configured to prevent emails from being forwarded. This is typically done by setting a flag on the email that indicates it should not be forwarded.
- Using a third-party service: There are also third-party services that offer non-forwardable email addresses. These services typically use a combination of technical measures, such as IP blocking and email filtering, to prevent emails from being forwarded.
It's worth noting that while these methods can prevent emails from being forwarded, they are not foolproof and can be bypassed by determined individuals.