By Twitter “ delete” does not mean “delete”
In the privacy policy Twitter in paragraphs “2.5 Twitter Data for Websites” and “4.2 Deletion” states:
1. The Company provides the option to delete account data.
2. After deactivating the account, the service stores data for another 30 days.
3. The service retains event log data for a maximum of 18 months.
Despite this, Twitter users may be surprised to learn that the service still continues to store deleted private messages. This applies to both deleted and blocked accounts.
This is confirmed by a study by security specialist Karan Saini, who studied the archive of his deleted Twitter account.
He found deleted private messages whose recipients are long-deleted or blocked accounts. Moreover, some messages were sent almost 3 years ago.