To archive mail from your mail server to Vaultastic, simply add journaling or mail routing rules to forward a copy of incoming and outgoing mail to the journal id on the vaultastic domain.
For example,
If your primary domain is acmecorp.com, and you wish to archive for john.smith@acmecorp.com, then the journaling rule should send a copy of all mail received and sent by john.smith@acmecorp.com to journal@acmecorp-com.vaultastic.com.
Vaultastic does not support email archiving for email ids hosted on public email networks such as Yahoo, Gmail, Rediff etc.
Vaultastic supports connectors for your domains hosted on GSuite/Gapps, O365, Hosted Exchange etc.