Originally posted by Sergiy (http://wpdev.uservoice.com/users/26024506-sergiy)
"
russian characters in email subject field are replaced by question marks when reply is sent.
Steps to reproduce:
1. send an email from gmail web interface with word "тест" as subject
2. download the email using phone default client (the subject is shown correctly)
3. press reply (subject is still correct)
4. send the email
5. check Sent folder - subject is displayed as ????
6. check email in gmail - subject is brolen as well

p.s. the phone language and settings are UK english. russian is used only as additional keyboard layout
"

The bug mentioned above got a lot worse since last WP7 update: if you reproduce steps 1-6, you will get a message with actually _broken_ e-mail headers. This is really frustrating, considering that this bug was there for more than 4 months.

Also, similar bug was spotted in native twitter client: then uploading a picture to pic.twitter.com, original tweet is displayed as "??????..." instead of non-english characters.