No username in mailman and bugzilla category

[pwnfoo]

Problem

The username / agent field seems to be missing from the mailman JSON returned by datagrepper.

The message right now looks like :

On the commops list, sskamath96@gmail.com replied to

Possible Solution

I do already see a email to username conversion in code but do not see e-mails getting resolved into the proper username(s).

It'd be nice to have this feature as right now, this bug is blocking the mailman badge

Edit :
Looks like the username lookup fails even for Bugzilla messages.