Please follow following steps to configuring a custom MX record through Helm.
STEP 1:
Login to Helm
STEP 2:
Enter the domain name into the search box along the left
STEP 3:
Click on "DNS Zone Editor"
STEP 4:
Click on the existing mail A record Click Delete
STEP 4:
Click on the existing MX record Click Delete
STEP 5:
Click "Add New". For the record type, choose A. For the record name, enter the hostname of your mail server Click save.
STEP 6:
Click "Add New". For the record type, choose MX. Enter @ for the record name. For the record data, enter the fully qualified domain name of your mail server Click Save.