Logic error with custom error codes and gsub

[jasonadamyoung]

Using 97, 98, and 99 with the line 144: code = code.gsub(/./,'')[1..2] results in what you'd expect, the code is gsub'd into 7,8,9 - resulting in unknown for any calls to the .reason method

I didn't know how you'd best like to fix this, so I didn't fork and patch. I just changed the codes to 9.9.7, 9.9.8 and 9.9.9 in my local copy just for uniformity with the smtp codes. (we get a lot of vacation replies and getting the reason string out is useful).

(thanks for this plugin btw, it's going to be helpful for us!)