1. open manage.liquidweb.com/manage/domains/ and search for the domain you are interest.
2.open the + sign and look for mail.somthing... - > copy this address for later use.
3.open https://cloudsites.mycpsrvr.com/ , log in > click on Mailbox > search for the domain you are interest.
4.Add mailbox > give it a name and pass.
5. in your website or web-config file - set the new SMTP details using smtp mail from stage 2. > user and password.
for example:
smtp server : mail.perform-365.com
user: mail@perform-365.com
pass: #####