Did you know that you can edit mail messages you’ve received? You might want to do this to replace a mail’s subject header with something memorable: removing “Re: Re: Re: Re: Re: Fwd: Plans for vacation”, for example, and replacing it with “Vacation hotel details”.
To do so, first ensure the mail folder list is visible at the left of the screen. This can be done by hitting Shift+Command+M. Then look for a mailbox called “Drafts”. This is where messages are stored when you write them but don’t immediately send them.
Find the message you want to edit within your Inbox, then drag it to the Drafts folder. Then open the Drafts folder and double-click the mail to edit it. Make any changes you want, then close the email, which will make a copy of it in the Drafts folder (don’t click the Send button!). You can then drag the edited copy back to your Inbox and delete the original unedited version in the Drafts folder.
Alas, this isn’t quite a perfect technique because the edited email receives a new time and date stamp, according to when it was edited, so will leap to the top of your Inbox as if you’ve just received it.