I have the same problem.
I tried to get some support and help here, but to no avail.
When I went back to Comcast email after complaining, the "sent" feature was there.
Now, (same day, but later on); it is gone again!!!!!!!!
Thanks for your reply.
I am accessing my email through my PC at home.
There USED to be several folders displayed to the left of the screen, but now there are none, yes, they are all gone.
I tried refreshing it and after the first time I complained and asked for help through Comcast's customer service, said folders reappeared for a brief time.
They are gone again!