Username validation in career section

Hello everyone!

We have a problem when candidate click on "Forgot Password" while logging in to external career section:

When candidate typing in the username that does not exist in our system, he recieves the message that email with details has been sent:

Email is sent, but actually - not sent. So could we somehow enable validation for "User Name" field, and as a result the candidate will recieve an error like "Such user name does not exists"

The link to Career_Section = https://stgciklum.taleo.net/careersection/ciklum_career/jobsearch.ftl?lang=en&portal=16105120549

Thanks in advance,

Vlad