iPhone4 just bought 3 weeks ago why cant email recipients receive videos

The recipient must be using a computer or device that is compatible with the video format captured by the iPhone. Anyone with QuickTime installed on their computer shouldnt have a problem. The iPhone 4 records in the MOV H.264 format, which is an open standard.
Im not aware of videos being truncated when sent via email. The iPhone 4 records 720p video at 30 fps, so it doesnt take long for recorded video to get quite large in size. Many email account providers have a 10MB overall message size limit but some have a 20MB overall message size limit. A video captured by the iPhone will be too large to send by your email account provider or it wont. If too large, a warning/error message is provided indicating the selected video is too large to send via email. If too large, the email will not be sent. There is an option to choose the overall size for a photo or photos selected to be sent via email, but I dont believe the same is provided for a video selected to be emailed. If not too large to send by your email account provider, it may be too large for the recipients email account provider. If your email account provider has a 20MB overall message size limit and the recipients email account provider has a 10MB overall message size limit, if you sent a video that is over 10 MB in size, the email will be sent but the attachment will not be received by the recipient, or the email wont be received at all.
 MacBook Pro 15" Intel Core 2 Duo/2.53GHz/4GB RAM/500GB HD Mac OS X (10.6.6)  iPod w/Video 30GB,  iPhone 4 32GB