If you ever need to change your CNAME there are a few things you should consider.
In order to ensure that old links sent out via email are not broken, you should:
You can use Add Additional Landing Page CNAMEs for detailed instructions on adding a secondary CNAME. This will allow all old links to still be functional.
Our recommendation is to change the sub-domain so that cookies can be shared. If you change the top level domain itself, the cookies cannot be shared and every lead would have to re-introduce itself to the new domain by either clicking on a link in an email or filling out a form.
go.mycompany.com > info.mycompany.com
Good! Cookies are shared.
go.mycompany.com > go.mynewcompany.com
Bad! Cookies are not shared.