CC-type fields when creating and replying to a ticket

We were formerly running RT 3.6.1 and are now running RT 3.8.1,
generally a good experience, but there is one small ‘issue’ I am
wondering about:

When creating a ticket the CC (and presumably AdminCC field too) accepts
a comma-delimited list of either email addresses or user login names,
even though the descriptive text (in both the rt-3.5 and web2 themes)
explains that it takes a comma delimited list of email addresses.
When replying to a ticket the two CC fields (CC and BCC) does not have a
descriptive text and so it is my assumption that they should work like
the CC and AdminCC fields during ticket creation, but these only take a
comma-delimited list of email addresses, not user login names, in RT
3.6.1 it was even assumed that anything entered here was an email
address, thus the system could attemt to send an email to something that
didn’t even have an ‘@’ in it, in RT 3.8.1 it seems that anything
without an ‘@’ in it is discarded before constructing mails.

My question is this:
Is the above described desired behavior, and if it is shouldn’t the
descriptive text of the fields be clearer as not to confuse end users?
Christian O. Knudsen
ComX Networks