It requires MX record pointing to IP address of your hosting product(shared/VPS) with us. For example, if you have windows VPS hosting with us, You are required to add following 2 DNS records at DNS zone of your domain.
i) Record type : MX
Record Name : [keep it blank]
Record Data : mail.domainname.com
MX priority : 10
ii) Record type : A
Record Name : mail
Record Data : 127.0.0.1(IP address of your VPS)
After adding above DNS records, you are required to host that domain from SolidCP or manually from SmarterMail.
[Note :- MX records propagation over the globe will take 24-48 hours.]
Note: It is recommended to verify email list before sending an email campaign.