Samsung Captivate :: Email Client Won't Auto Check Email

Does anyone else have the same problem? When I use the default email client from captivate, even when I set the checking period as every 10mins, I won't get new emails unless I open the app and manually refresh, well, except the one of gmail. This happens on my yahoo email, hotmail and my school email, which all worked fine on my old iphone. People have talked about yahoo mails won't be accessible through wifi from Android, which happens on mine too. But even when I was at 3G, the email client won't auto check it either. I have tried K9 email client, it doesn't work either. The only thing I find work is the MailDriod, but the function of this app is very limited, it won't even open attachments by default. Does anyone else here have the same problem, or maybe an idea to fix the default email client?Also, I find when I use the ear set make calls, when I try to click the button on the ear set, it won't hang up the call as my iphone would. Is this a bug or just something Andriod can't do? The button on the ear set seems quite useless with Captivate, it can only control to play or pause by single click when play music, won't do song change when doule click it.