Editing Repair your sending reputation (section)

=== 2. Slow Down the Frequency of Your Sends ===
To help improve inbox placement, it is advisable to pause all email sends for one week. This period acts as a cool-down for your domain. Upon resuming, start by sending emails only to contacts who have clicked a link in your email within the last 30 days. This helps by focusing on engaged users. Make sure you do not send over 25,000-50,000 emails in one day initially.

If you observe improvements, incrementally expand your reach to include contacts who opened or clicked emails within the last three months, eventually extending this to six months.