I've reviewed discussions on username vs email for login form but couldn't find any reference to a similar case.

The website I'm working on has large number of existing clients who can only use 'assigned' username to log in to the site.

However, brand new users can use their email address as their username.

We thought of a few label options:

'Username or email' We worry if existing clients will attempt to log in with their email which they're not allowed to (we have a long term plan transitioning them to opt to use email address instead of assigned username - but not anytime soon).

'Username' Technically this refers email address as in 'username', plus legacy clients' username, however, it is not clear for brand new users who don't have assigned username.

Any thoughts on getting around this gracefully?

Thanks in advance.

1 Answer 1


Whilst it may be better practise in the long run to migrate all legacy users to the new system, the MMORPG site Runescape has a system to deal with legacy users. In their system, they check to see if the user is on the legacy system once the user clicks log in, if the user enters their email when they should enter their username, it alerts them after they click log in and the user must enter their correct details again.

However their are pro's and cons to the above system.


  • The user knows not to enter the wrong details again as it is inconvenient for them to do so next time
  • The response answers how to get around the above question


  • As a pro but also a con, it causes inconvenience for the user to re-enter their details again after the page refreshes

What I think you should do

In no way am i an expert with UX, but if this was my system, i would wait for the user to lose focus with the username textbox, then run a quick DB query to see if they are a legacy or new style user. If they have entered information that is wrong, present a label and red underline to tell them that they need to enter their email or username

This removes the con to the above method, as the user doesn't actively have to click log in before being alerted to the fact they logged in wrongly.

Another Option

If you are to follow one of your options above, i would personally write Email or Username (Legacy) in the textbox to alert the user to the different types of logins.

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