I think what is happening with the duplicate messages, is that some of us must be hitting "reply to all" or actually clicking on forward, then it will forward everything in that email previous to the message you are actually writing too. Sometimes it helps if we didn't see the first question to understand the last persons response, other times I also feel it's annoying to have repetitve messages and have to ready everything twice.
As far as the "gibberish" that has something to do with the way the mail is being sent and what program the messenger is using to send their mail. Sometimes this contains such things as <font font>, etc. That needs to be addressed through your setting in your mail tools.
I certainly hopes this helps all ...I am not a computer whiz, but I do know a little bit. So if you have a setting in your Internet software, find mail, then tools or just find tools and see how your outgoing mail is being sent.
It's just another little headache to add to our aches and pains.!! Sorry !!