some users complained about corrupt pdf files sent using squirrelmail. i noticed in most cases enconding was wrong, it was text/download, sending a lot of binary code and different newline breaks from the original causing the corruption.

this only happens in some computers with firefox, i was able to correct it in a computer after reading
basically editing mimeTypes.rdf and deleting all wrong pdf entries, leaving only application/pdf

this is just in case someone had the same problem.