Problems replying to emails from Lotus Notes or Entourage

When I reply to an email which was sent to my Bold from either Entourage or Lotus Notes, my reply email loses all paragraph/line breaks and therefore appears messed up for the recipient who reads it in Lotus/Entourgage.

I haven't had this issue replying to emails from other mail clients and I didn't have this issue on my old 8300 Curve...it's only started happening once I switched over to the Bold.

I'm running v4.6.0.282 on BIS and I don't have any third party apps installed. Has anyone else had this issue or have any ideas on how I could resolve it?