When you share a link to your email, by default, only people with your domain can view the link, and it will never expire (@gmail.com users will default to anyone with a link).

You have the following privacy options for shared email links you create:

You can control who can see a shared link and the length of time it can be viewed. When a link expires, the shared email will no longer be viewable.

You can change the default settings for this in your Mixmax Shared Email settings.