Is appending the company e-mail domain to a textbox good UX?

Question

My application has companies that have many users. To login to the application, they use their e-mail address. The company has a preferred domain name (e.g. google.com). Is it good UX to append this preferred domain to the email field to reduce the amount of typing when creating/changing their email address?

Here's an example: http://jsfiddle.net/kwHx2/

The only edge case would be companies that hire contractors (or have a sub-domain'd e-mail) and need a different domain. The approach I took in that example is when the user enters an @, the appended domain is removed. I'm not really sure if this is obvious to the user. Alternatively, I was thinking of having the user clicking on the domain or having (change) beside the domain to trigger the change.

Answer 1

Google does something similar when you are setting up a new android device. Their solution doesn't involve having the domain name outside the box though. It is presented as a suggestion within the text field. The user types their email address and then when they hit the @, the rest of the field is auto populated with gmail.com after the field (with the entire addition highlighted so if the user wishes to overwrite it all they have to do is keep typing). Something like this:

^{download bmml source – Wireframes created with Balsamiq Mockups}

It presents the functionality in a way that requires no additional effort (regardless of whether you choose to use it or not) which makes it much more elegant in my opinion.