email as username, pros and cons

[eluser]steelaz[/eluser]
I was searching net for some research done on this topic but couldn't find anything. Any thoughts?

[eluser]James Gifford[/eluser]
It could cause confusion if the user changes or loses their email address.

[eluser]Michael Wales[/eluser]
I like to use the email address as username if it will not be displayed anywhere publicly. If it will be displayed publicly, I always use a username (or still use email but allow the user to set a display name).

As far as people changing/losing their email address - in my personal experience, I am much more likely to have more usernames than email addresses. It's always harder for me to remember what username I registered with, than if it asked for the email address I used.

[eluser]Lone[/eluser]
I like the use of emails as well as a login tool for the same reason Michael just stated. But we have been caught out before with one client that needed to have the same email address for multiple accounts which of course made it difficult to use this solution. But that being said it will work out fine for 95% of cases.

[eluser]steelaz[/eluser]
I was going to use emails and let users change displayed name to whatever they like. I guess I will have to setup routine for users to able to change their email.

[eluser]MadZad[/eluser]
Also keep in mind the situation where a user loses their email address suddenly, like switching jobs or internet providers. Be sure that these folk would be able to change their email addresses, whether or not you use them as logins. I remember encountering a company that required confirmation to the email address on record in order to modify a profile - including changing email. Duh.

A reason you'll hear a lot of good advice, sometimes conflicting, is because there are different solutions for different user bases. My advice would be to leave the computer, grab a beverage, forget all about programming, and envision yourself as your users. Then think about the ways they'd interact with your site/application. Sketch out a few page flows with good old paper and pencil, then run through the flows in your mind with a user's mindset. If you get annoyed, improve the page flows. Works for little details like whether or not to use email as a username, and much bigger issue.

Good user centered design also makes for a lot less maintenance programming. Then again, bad UCD is useful to keep the customer base low...