Every household in Sweden received a 30 page-brochure in the summer, I guess, of 1967. Then, on September 3 at 4:49 AM, all driving stopped on Swedish roads. Very slowly, the buses, taxis and lorries on the roads moved to these roads' other sides — still facing the same direction, motionless now for about 10 minutes.
At 5:00 AM, traffic resumed. After some 230 years, Sweden's vehicles had changed from being driven on the left to being driven on the right side of the road.
Now, if you want to change an email from being sent from one email address to being sent from another in MailMate, there's a (roughly) 1-page brochure; you don't have to make the change permanent for 230 emails (or two):
›› Edit the name, address and, perhaps, comment in the From: line of just this message you send. In MailMate, you can edit the From: line of any email you compose without configuration and permanence.