Some domains, email addresses or even name prefixes may negatively affect deliverability and sender’s reputation. SFMC has a tool – List Detective (LD) – to block inactive domains or known spammers emails. This feature is not enabled by default and to request it log a case with the SF support.
List Detective for Triggered Sends
The LD automatically checks against an invalid or a known troublesome email addresses. It works while importing subscribers, sending a a data extension, sending a triggered send or collecting data with Web Collect forms. Despite a custom allowance of specific usernames (whitelisting LD set in the Admin panel for a Business Unit), it won’t clear email addresses used in triggered sends. To whitelist LD for triggered sends – raise a ticket to the SF support.