Microsoft has to have your customers email address so they can market to your customers and cut you out of the loop. This is why you are referred to as a "Valuable Partner" . You have been trained now, with the branding iron, so you will not make the same mistake again and register under your own email address or an alias for your customer.
You can go to https://signup.live.com and create an account using the customers real email address ie: ******@warnerbros.com so you do not need a bogus hotmail/skype/outlook/live address.
The problem for we "Valued Partners" is that I believe a validation email is sent to that address and action needs to be taken to activate the account and product. They want the names of the first born, favorite author, childhood hero, name of your prom date, size of your underwear or other information, along with age, ****, phone number or other demographic and personal tracking information. We're often doing this work at the clients desk, then we have to go fetch them to respond to this address, and answer the foolish questions, which cost valuable time and money.
We buy Office 2013 Home and Business for $219, and have to sell it for $219. The profit margin is zero. After we install it, it ends up being a negative profit. We end up losing money every time we upgrade a SOHO client. We only have 12 working hours in a day, and its silly to have to 'spend' 20 minutes with every activation.
Yes, we could TRY to sell them open license, the same product for $100 or more extra, but this is SOHO, and all they want to do is go back to work (and find out all the buttons have been changed and the ribbon button hidden by default). If we stick around, it end up costing another 30 minutes to tweek the install so they can at least find the new ribbon with the mixed-up shortcuts.
MS should really send some scouts out in the field to try to make a living selling this stuff and get some real world feedback from the techs in the trenches, and the poor end-users who are subject to an endless shuffling of menu items and feature removals, like MS Picture manager..... but that is another rant.