Postmark stores email content, events(e.g. delivery, click, open), and metadata for 45 days. After 45 days, Postmark deletes email content and related metadata for all delivered messages. Postmark stores aggregated statistics forever.
Postmark stores blocked inbound messages for 45 days.
For bounce reports, Postmark stores email metadata and the bounce reason for up to 1 year. Postmark retains metadata like Recipient, Subject, Sender, Date, and Bounce reason. This is key data for spam and delivery monitoring, and to have a record if end-users ask about why/how they received an email. After 45 days, Postmark deletes the content of the bounced email.