mail and Mail_Mime question

Hello, I try to send e-mail message in HTML format using Mail_Mime class. HTML has embedded stylesheet with some CSS class definitions like ".clsWhite { color: #FFFFFF; }" (starting from new line and without quotes). The problem is that I receive e-mails where leading dot symbol if front of CSS class name is removed, so ".clsWhite" becomes "clsWhite". It happens when I test on my local computer with WinXP, MS SMTP Service. It happens whet I upload to the hosting company's server which is *nix. I noticed that sometimes it depends on what CR/LF combination was used for building mime messages. So why does it happen? Is there any solution for this problem? Thanks