gistfile1.m

NSString *htmlBody = @"you probably want something HTML-y here";
		
NSString *escapedBody = [(NSString*)CFURLCreateStringByAddingPercentEscapes(kCFAllocatorDefault,	(CFStringRef)htmlBody, NULL,  CFSTR("?=&+"), kCFStringEncodingUTF8) autorelease];

NSString *mailtoPrefix = [@"mailto:?subject=Some Subject&body=" stringByAddingPercentEscapesUsingEncoding:NSUTF8StringEncoding];
NSString *mailtoStr = [mailtoPrefix stringByAppendingString:escapedBody];
		
[[UIApplication sharedApplication] openURL:[NSURL URLWithString:mailtoStr]];