[corresation]

That exactly the sort of assumption you can't afford to make

Okay so what if the transition took five days? How about thirty days? In the absence of seemingly any warning information at all on this, how does one ever perform such a change?

Let's take it further -- what if adding a user took down your email for a month? That is just as rational as removing an artificial limit is ("Oh didn't you know? You pushed our global user database past the threshold so we had to migrate platforms"). How about if you send an email that you CC to ten people and that takes your email down for days?

If this wasn't an expected behavior, and is seemingly a mere administration change, there is no universe where it can be pinned on the user. Doubly obvious given the confused responses of customer service.

[bigiain]

Exactly my point. If you're making changes to mission-critical things, you need to have both reliable information on how long those changes will take, as well as rollback plans to cover the risk of things going wrong.

Randomly clicking things like "change my email system" buttons, then complaining afterwards that it didn't work how you expected is the sort of mistake most of us have made at least once.

Once you've suffered through those mistakes, you tend to view phrases like "expected behavior" and "seemingly a mere administration change" a lot more suspiciously.

If it's mission critical, don't "assume", don't "expect" - things are often not as they "seem". As they say "Trust, but verify." Yeah, Google (or Rackspace, or MessageLabs) will _presumably_ "get it right", but when the consequences of "presuming" are business-destroyingly-high, verify the presumptions first.