How to point my mail service here
To start using the email accounts associated with your domain name, you need to point your domain’s MX records to our email service. You can see which are the correct default MX record in Site Tools > Domain > DNS Zone Editor. There select the MX tab and choose Switch to system default MX records. The correct records will be displayed in the tool. Use the Create button in that tool to create and start using the correct MX records.
If your domain is pointed to external name severs, copy the MX records listed as the expected defaults for your domain in Site Tools and add them in the DNS zone of your domain, wherever you manage it. You can copy the MX records details by scrolling down the page and finding the records with type MX:
Delete all other MX records for your domain name and leave only the ones above.
Once you point your MX records, there is a standard propagation period that may take up to 72 hours before your mail service is properly switched to SiteGround.