This usually happens due to filtering or blocking in your mailbox settings. Check these:
• Go to Settings, Mail, Junk email. Review Blocked senders and remove any valid senders
• Add your bank or institution domains to Safe senders
• Check Junk Email and Deleted Items for missing messages
• Go to Settings, Mail, Rules. Remove any rule moving or deleting emails
• Check Focused Inbox or Other tab for misplaced emails
Outlook filters messages based on safety and rules. Fixing these settings helps restore normal delivery.