Rubbish or corrupted emails extracted

[dab]

I am using Thunderbird, and when I extract emails from a folder, I get about 2 or 3 thousands of rubbish or corrupted emails, such as cacbxne-ujccdgufzuttrdzutorvrpgq_cy57kq ... .gmail.com and
[email protected]
I have tried re-building my Thunderbird database. I have also tried looking for these emails in Thunderbird, and they are not there. What is causing these spurious emails and how can I stop this?

 

[stanbusk]

I guess the file you are processing is a binary file, isn't? The only binary supported as RTF, PDF, Excel and Word files.