This is a totally cool tip.
If you use Mail you can click to highlight any message within the Inbox, hit Command + C and then hit Command + V to paste the message contents into a text editor such as TextEdit. Open a blank page in your text editor so the computer knows where to paste and click inside the text editor before you hit Command + V. This doesn’t work with Microsoft Word but it worked with other Mac compatible word processing apps I tried.
By clicking to highlight a message I mean just click on the message in the list. You don’t have to open it.
If it is a multi-part message as in my example (the arrow to the left of the message so indicates) the contents of all of the messages will be pasted at the same time, in order.
By highlighting multiple emails in the Inbox, then hitting Command + C followed by Command + V, you can paste the content of all of them into a new single document within the editor and they will appear one after the other.
In my example I have copied the receipts I have received from the App store. Now I can delete them from my email and still have a record should I need it.
I hope you like this tip as much as I do.