Deleting vs. archive
You can only delete contacts - there is no archive option. This means if deleted contacts are re-added they are treated as new contacts. (Re-adding archived contacts typically would restore all history and contacts are not treated as new.)
Loss of contact activity history
You permanently lose all history for deleted contacts. (email opens, sends, clicks, etc).
Aggregate email stats are never removed even if contacts the email was sent to no longer exist. You'll see for example that there were X clicks in an email but when you drill down you'll see fewer contacts if some of the contacts that are part of that metric are deleted.
Contacts with invalid emails
There is no need to delete contacts with invalid emails. Invalid and unsubscribed contacts don't count towards your total contact count and as such they aren't used for billing.
Unsubscribed and spam reported contacts
Contacts with consent status "revoked" or "spam reported" cannot be deleted. This restriction is in place to prevent these contacts from being accidentally re-added to the database as subscribed contacts, which could create spam complaints and compliance issues.
If you re-import contacts who had been deleted they will be added as new contact records. Unsubscribed contacts cannot be deleted and during a re-import the unsubscribe status is kept. Unsubscribes cannot ever be overwritten in bulk.
Marking contacts as unsubscribed
Instead of deleting contacts you could mark them with "revoked" consent state (unsubscribe them). That way history is kept but contacts will not receive any emails from you going forward. Read more: how to bulk unsubscribe contacts
How to delete contacts?
To prevent accidental deletion of a large number of contacts you can only delete contacts that are shown on single page, for example 25 or 50 at a time. To do this, follow the instructions described on the "how to bulk edit contacts" page.
Delete large number of contacts in bulk
Mark the contacts you want to delete with an internal list or add them as part of a filter.
Contact support via chat and let us know how you marked the contacts to be deleted (name of internal list or name of filter) and confirm the number of contacts to be deleted.
We will delete the contacts for you.
Deleting is permanent
We keep data backups for 30 days but recovery from the backups is a paid service. After 30 days contacts are removed from backups with no option to recover them.