Upon realising an accidental deletion, head quickly over to 'trash', locate the email in question and use the right click function to pull up your options. Then, click 'move to' and the location you would like to place the email in - whether that's back into your inbox or a different folder.

However, of course, in some cases it may be over the crucial 30 day deadline before you realise you actually do want to recover that important email. What are your options in this case? 

Bad news - there is a good chance your email has been irrevocably deleted. However, you do have a recourse of action available to you. You can email Google's support team to ask whether there is a possibility of getting the email back. 

Although this service is aimed more at emails that have gone missing as a result of your account being compromised, if in need, you can try Gmail's missing email page. Here, you need to fill in a form providing information. Do this as soon as you realise the email is MIA - the longer you wait the less likely the possibility of retrieving it. 

Similarly to Gmail, in Outlook you also need to head over to the 'deleted items' box, in the case of a deleted email, or other item like a contact or calendar event. Once you've located the deleted email in the folder, simply click restore to recover it. This folder may also be labelled the 'trash' folder, depending on which version of Outlook you're using. 

If you can't locate the email in the deleted items folder, the next place to head is the Recoverable Items folder. This folder is generally hidden, and is where emails are directed when either delete an item from the deleted items folder, empty the deleted items folder, or permanently delete an item by pressing Shift+Delete. 

Before attempting to access the recoverable items folder, it has to be noted that if you are using a version of Outlook where you have a 'trash' instead of a 'deleted items' folder, this folder doesn't exist, and you won't be able to recover emails beyond your Trash folder. 

For users of the version that supports the recoverable items folder, once you've clicked on the 'Deleted items' folder, make sure the 'Home' tab at the top of the page is selected, and you should see the option 'Recover deleted items from server'. If you don't see this option, then unfortunately your version of Outlook doesn't support this option. 

Once you've clicked this, you should see a list of all the emails that you can recover. Simply select the one of your choice, click 'Restore Selected Items' and then 'Ok'. From here, the email will be placed back into your 'Deleted Items' folder, from where you move it to a folder of your choice.

If the email isn't here, all hope is not lost - just yet. As most email servers will make backup copies from time to time where they are kept for a short while, it might still be possible to restore it by contacting support here.