PHP: imap_savebody() breaks long lines

I attempt to parse an email message whose body is in csv format.

The email supposedly has this content:

,111111111111111,Abcde Abcd,,abcde@abcdefghi.com.au,61352722827,13/04/2012,14/04/2011,Abcd Abcdefghi,
,111111111111111,Abcde Abcd,,abcde@abcdefghi.com.au,61352722827,13/04/2012,14/04/2011,Abcd Abcdefghi,

But imap_savebody() saves it like this:

,11111111111开发者_StackOverflow1111,Abcde
Abcd,,abcde@abcdefghi.com.au,61352722827,13/04/2012,14/04/2011,Abcd
Abcdefghi,
,111111111111111,Abcde
Abcd,,abcde@abcdefghi.com.au,61352722827,13/04/2012,14/04/2011,Abcd
Abcdefghi,

The encoding is 7BIT as outputted by imap_fetchstructure. Anyone knows why this happens?