Logged In: YES 
user_id=29957

Positive. For instance, here's a raw header:
Subject: [dev378]
=?utf-8?q?Create_new_=22monitored_events=22_table,
        _poll_in_cs_control_panel?=

Note that ascii 0x22 is "

kedder, in a comment below, noted that anything outside
-a-zA-Z0-9!*+/[].,
is encoded. This should be extended to cover single and
double quotes.