MithiDocs

Step 2: Add a route for the Vaultastic domain

On the outgoing mail server, add an SMTP route to route all mails for your Vaultastic domain to o365-v4.vaultastic.com

For example, if your Vaultastic domain is acmecorp-com.vaultastic.com, then the route should be as follows:

Route all mail for acmecorp-com.vaultastic.com to  o365-v4.vaultastic.com