You may want to recall or resend a message that you've already sent.
To get started, go into your sent items folder in the navigation pane. Find the message that you want to resend and double click on it. If I wanted to send this to somebody else, maybe I didn't have the original copy in my inbox anymore, only the sent folder, click file on the top left-hand side of the email message, click info on the left, resend or recall, and then resend this message. It pops open a brand new copy of the email. From here you can recall an email, though it's important to note that it only works if the other recipient is using Outlook, so this is perfect in an Office 365 environment because you know that all of your coworkers are most likely using Outlook. If it's an external email address, you won't know if it worked or not. But to get started, find the email that you want to take back in your sent items folder, the sooner the better so chances are low that somebody's already opened it. Double click on the email, change to the File ribbon tab, click info on the left, resend or recall. You can choose to delete unread copies of this message or I can delete it and replace it with a different message. You can also decide to be notified if the recall fails or succeeds for each person. Click OK. Closeout of this and go back to the inbox.
The hyperLink below is to Linked-In Learning video where you can watch the full instructions and guide to recalling or resending an email after you have already sent.