Clean an Email backup file

[TTN]

Hello, I am with a non profit and trying to salvage old emails from backup files. 1. The old email program is not available any longer. 2. I simply changed the file ext to txt. 3. I can read all the emails. 4. There are a lot of mime files in this text file. 5. I would like to filter out or delete these lines of mime code. 6. I do not have programming experience and this project is not worth learning one. 7. The file is 43000 lines. The only thing I thought of was that these lines of code are not in the dictionary. Could I filter the file with the word dictionary? Thank you for this forum and any directions would help. Tom