This article explains how to hide deleted messages that appear gray and with a strikethrough line in Outlook folders. This information applies to Outlook 2019, Outlook 2016, Outlook 2013, Outlook 2010, and Outlook for Microsoft 365.
How to Add Strikethrough Text Formatting Option to Microsoft Outlook Emails
In IMAP accounts, messages aren't immediately deleted when you press the Delete key or move them to a Trash folder. Instead, they're marked for deletion until you clean up the folder. Messages marked for deletion in Microsoft Outlook are grayed out with a strikethrough line, but are still visible. If you don't want to see these messages, tell Outlook to hide them.
Open the folder where you want to hide crossed-out messages, for example, the Inbox folder.
In the Current View group, select Change View.
