Here’s How to Cancel a Meeting the Right Way – Both Sides of the Table: in advance, with plenty of warning, ideally not the same day or the day before, bearing in mind the possible multiple attendees.To this I want to add:
Please use the calendar app!I.e. if the meeting was placed in a shared calendar like Outlook/Exchange or Google Calendar, please cancel it in the shared calendar app.
It sucks when I hurry to a meeting -- where "hurry" may mean finding a quiet room to dial into a teleconference or log into Skype or ... -- and then sit on hold -- because the cancellation message was sent by ordinary email, and the shared calendar app was not updated. So the event still appears in my calendar.
This sucks because I am often behind in reading email. Whereas automatic updates to the shared calendar app will be ... automatically updated ... so at the time of the meeting I can see that it is cancelled or not.
I.e. a shared calendar is automatically filtered and classified according to event time. Email is not.
Ideally, a smart assistant like Google Now might be reading your email Inbox, applying natural language recognition to cancellation messages, and automatically marking the shared calendar event cancelled if a human-written email has recognizably cancelled it. "Events from Gmail"   automatically does this for things like airline flights or hotel reservations, stylized so that it can recognize them. I haven't yet seen anything smart enough to recognize arbitrary human written cancellations. Plus... this usually happens with my company Outlook/Exchange calendar, and AFAIK I am not allowed to send all of my company email to Google. Nor am I aware of any Outlook plugin.
Companies often use a single shared calendar. (Except for a short time after an acquisition, as IT systems merge.)
When there is no single shared calendar, i.e. when a meeting involves people who use different calendar systems (possibly including paper), you may have to fall back to email. But even then, many shared calendars send email when a meeting is cancelled, e.g. Outlook may update the Outlook/Exchange shared calendar, and send email to the Google Calendar users. The stylized form of such automatic emails increases the chance that a smart assistant may be able to recognize it.
While I am at it:
Sometimes having a meeting silently disappear from your calendar can be confusing: "I could swear that I had a meeting at 10am..." In an ideal world, such a cancelled meeting might still show up in your shared calendar application, but be marked as cancelled, grayed out, possibly with an indication as to when it has been rescheduled.
It would be nice if email "conversations" could be attached to a calendar item.
Many distributed applications are store-and-forward message based, e.g. different calendar instances may be connected by sending email messages back and forth. As opposed to sharing direct access to a database.
It's not the email message that cancels a meeting that sucks. It's the lack of automatically updating the calendar item that sucks.
(Email based messaging for distributed applications would be even better if email was secure.)