I cannot figure out how to post/report a problem here.

I am posting a problem.  Today I sent a new email to my sister.  It went into my sent box and she received it.  A few hours later she replied but I received the reply in my sent box attached to the original letter.  It never went to my inbox.  I only found it by accident when she called to ask if I got her reply.  Is this a known problem.  I have emClient version 7.1.33101.0

The received message is actually in your Inbox, but because of conversations, messages related to the one you sent will also be displayed in the Sent folder as well. If you go to Inbox, you will find the same conversation there.

If you disable conversations (Menu > View > Conversations) you will be able to see an unfiltered view of what is in each folder.