I know of a few companies that front-end their email with ProofPoint [1] but I have no idea how much it costs, probably a lot. It can quarantine anything suspicious. It also lets the admin know who clicked on what links in emails.
It rewrites links to its own tracking endpoint It also doubles as a DLP
Data Loss Prevention meaning it can be taught to look for organization specific data that should not be in email. It can also give you reports on who is receiving the most abusive emails
meaning they may be targeted by attackers.[1] - https://www.proofpoint.com/us
