If you need to log in to Stackmail - SIRSTEVEHQ CP's free webmail available with all hosting packages - the URL they need is www.Stackmail.com.
Frequently Asked Questions
What CNAMEs can I use to point webmail to my own brand?
Using the tool within My Brand adds the relevant CNAMEs for you so there's no need to add these manually. A branded webmail URL will be given the CNAME:
webmail.example.com -> CNAME -> stackmail.com
A branded URL with an SSL applied to it will be given the CNAME:
webmail.example.com -> CNAME -> webmail.stackcp.com