Possibility of Recovery:

The good news is that the deleted or lost emails and other Outlook objects are completely recoverable. When you deleted any item using Shift + Del key combination or by emptying the ‘Deleted Items’ folder, it does not get removed permanently. It is still recoverable using appropriate tools and mechanisms.

When you delete an email from your system, it remains physically intact. The operating system does not have any way to find out the location of the email. The mail is deleted from the index of PST file. Thus, Microsoft Outlook can not locate the file due to missing file pointer.

Take Quick Action:

When you unintentionally remove any item from your Outlook PST file, you should take quick action to increase the chances of successful recovery. The more your work on affected PST file, the more you increase the chances of data overwriting and permanent data loss.

Windows hard drive constantly overwrites the files to free up disk space and to store new data. If the drive is full and it does not have enough free space to write new data, it can overwrite the deleted emails.

Restore From Backup:

Creating backup and regularly updating it is the best way to safeguard data against loss. It helps you to recover deleted emails in case of any disaster.

If Backup is not Available:

If you do not have complete backup of your Outlook PST file, the problem can become quite serious and difficult to handle. At this point, deleted mail recovery softwares come for your help. You can use any software for backup purpose. Just google it and you will find collection of free and paid softwares.