If you have a custom domain linked to your Squarespace 5 site, you can also use a custom email address. For example, if your domain is www.sampledomain.com, you can use an email address like firstname.lastname@example.org.
Squarespace doesn't host email, but you can create a custom email address with G Suite. This gives you free web-based email that works just like Gmail. To learn more, visit Setting up G Suite (previously Google Apps) for Squarespace 5.
Custom email addresses work with Squarespace domains and third-party domains.
Squarespace 7.0 comparison
If you want a new custom email address through G Suite, this might be a good time to consider moving to Squarespace 7.0. Squarespace 7.0 has more sophisticated options, including the ability to register new G Suite accounts directly through the Squarespace interface. Learn more on our Squarespace 7.0 help site.