mikel/mail — pull request #439 by ochko (2012-10-10 04:48:49+00:00)
Title: Should ignore invalid or undefined characters

```ruby
Iconv.conv("UTF-8//TRANSLIT//IGNORE", charset, body_text)
```
It ignores invalid or undefined chars.

In ruby 1.9 it should be:
```ruby
body_text.encode(Encoding::UTF_8, :undef => :replace, :invalid => :replace, :replace => '')
```